diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9729181..d23f216 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,16 @@
 # did-io ChangeLog
 
+## 3.0.0 -
+
+### Changed
+- **BREAKING**: `parseDid` changed to return `scheme` and `method` instead of
+  only `prefix`.
+
+### Added
+- **BREAKING**: `CachedResolver` now validates DIDs before resolving them.
+- `CachedResolver.use` now accepts a second optional method parameter.
+- Tests were added for the new validators.
+
 ## 2.0.0 - 2022-06-02
 
 ### Changed
diff --git a/README.md b/README.md
index 1c18d0f..18894b8 100644
--- a/README.md
+++ b/README.md
@@ -80,7 +80,8 @@ const resolver = new CachedResolver({max: 100}); // defaults to 100
 On its own, the resolver does not know how to fetch or resolve any DID methods.
 Support for each one has to be enabled explicitly. It uses a
 [Chai](https://www.chaijs.com/)-like plugin architecture, where each driver
-is loaded via `.use(driver)`.
+is loaded via `.use(driver)`. Optionally method can be passed in as the second
+parameter.
 
 ```js
 import * as didKey from '@digitalbazaar/did-method-key';
diff --git a/lib/CachedResolver.js b/lib/CachedResolver.js
index bfd0673..04dec8b 100644
--- a/lib/CachedResolver.js
+++ b/lib/CachedResolver.js
@@ -1,7 +1,9 @@
 /*!
- * Copyright (c) 2021 Digital Bazaar, Inc. All rights reserved.
+ * Copyright (c) 2021-2022 Digital Bazaar, Inc. All rights reserved.
  */
+import {DidResolverError} from './DidResolverError.js';
 import {parseDid} from './did-io.js';
+import {validateDid} from './validators.js';
 import {LruCache} from '@digitalbazaar/lru-memoize';
 
 export class CachedResolver {
@@ -20,15 +22,20 @@ export class CachedResolver {
     this._cache = new LruCache({max, maxAge, updateAgeOnGet, ...cacheOptions});
     this._methods = new Map();
   }
-
-  use(driver) {
-    const methodName = driver.method;
+  /**
+   * Registers a driver for a did:method.
+   *
+   * @param {object} driver - A did method driver.
+   * @param {string} [method] - An optional method.
+   */
+  use(driver, method) {
+    const methodName = method || driver.method;
     this._methods.set(methodName, driver);
   }
 
   /**
    * Gets the DID Document, by selecting a registered driver based on the DID
-   * prefix (DID method).
+   * method (DID method).
    * Either `did` or `url` param is required.
    *
    * @param {object} options - Options hashmap.
@@ -42,10 +49,7 @@ export class CachedResolver {
    */
   async get({did, url, ...args} = {}) {
     did = did || url;
-    if(!did) {
-      throw new TypeError('A string "did" or "url" parameter is required.');
-    }
-
+    validateDid({did});
     const method = this._methodForDid(did);
 
     return this._cache.memoize({
@@ -67,7 +71,10 @@ export class CachedResolver {
   async generate({method, ...args}) {
     const driver = this._methods.get(method);
     if(!driver) {
-      throw new Error(`Driver for DID method "${method}" not found.`);
+      throw new DidResolverError({
+        message: `Driver for DID method "${method}" not found.`,
+        code: 'methodNotSupported'
+      });
     }
 
     return driver.generate(args);
@@ -80,11 +87,14 @@ export class CachedResolver {
    * @private
    */
   _methodForDid(did) {
-    const {prefix} = parseDid({did});
-    const method = this._methods.get(prefix);
-    if(!method) {
-      throw new Error(`Driver for DID ${did} not found.`);
+    const {method} = parseDid({did});
+    const methodDriver = this._methods.get(method);
+    if(!methodDriver) {
+      throw new DidResolverError({
+        message: `Driver for DID ${did} not found.`,
+        code: 'methodNotSupported'
+      });
     }
-    return method;
+    return methodDriver;
   }
 }
diff --git a/lib/DidResolverError.js b/lib/DidResolverError.js
new file mode 100644
index 0000000..0bdd439
--- /dev/null
+++ b/lib/DidResolverError.js
@@ -0,0 +1,20 @@
+/*!
+ * Copyright (c) 2021-2022 Digital Bazaar, Inc. All rights reserved.
+ */
+
+/**
+ * Error for throwing did syntax related errors.
+ *
+ * @param {object} options - Options to use.
+ * @param {string} options.message - An error message.
+ * @param {string} options.code - A DID core error.
+ * @param {object} options.params - Params to be passed to the base Error Class.
+ *
+ */
+export class DidResolverError extends Error {
+  constructor({message, code, params}) {
+    super(message, params);
+    this.name = 'DidResolverError';
+    this.code = code;
+  }
+}
diff --git a/lib/did-io.js b/lib/did-io.js
index 6d02b1d..6e2d068 100644
--- a/lib/did-io.js
+++ b/lib/did-io.js
@@ -194,22 +194,34 @@ export function _methodById({doc, methodId}) {
 }
 
 /**
- * Parses the DID into various component (currently, only cares about prefix).
+ * Parses the DID into scheme and method components.
  *
  * @example
  * parseDid({did: 'did:v1:test:nym'});
- * // -> {prefix: 'v1'}
+ * // -> {scheme: 'did', method: 'v1'}
  *
  * @param {string} did - DID uri.
  *
- * @returns {{prefix: string}} Returns the method prefix (without `did:`).
+ * @returns {{scheme: string, method: string}} Returns the scheme and method.
  */
 export function parseDid({did}) {
   if(!did) {
     throw new TypeError('DID cannot be empty.');
   }
 
-  const prefix = did.split(':').slice(1, 2).join(':');
+  const [scheme, method] = did.split(':');
 
-  return {prefix};
+  return {scheme, method};
+}
+
+/**
+ * Determines if a DID has URL characters in it.
+ *
+ * @param {object} options - Options to use.
+ * @param {string} options.did - A DID.
+ *
+ * @returns {boolean} Does the DID potentially have a query or a fragment in it?
+ */
+export function isDidUrl({did}) {
+  return /[\/#?]/.test(did);
 }
diff --git a/lib/index.js b/lib/index.js
index f99bb49..ae81f71 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -5,9 +5,12 @@ export {
   approvesMethodFor,
   findVerificationMethod,
   initKeys,
+  isDidUrl,
   parseDid
 } from './did-io.js';
 
 export {CachedResolver} from './CachedResolver.js';
 
+export {DidResolverError} from './DidResolverError.js';
+
 export {VERIFICATION_RELATIONSHIPS} from './constants.js';
diff --git a/lib/validators.js b/lib/validators.js
new file mode 100644
index 0000000..5231014
--- /dev/null
+++ b/lib/validators.js
@@ -0,0 +1,83 @@
+/*!
+ * Copyright (c) 2022 Digital Bazaar, Inc. All rights reserved.
+ */
+import {isDidUrl} from './did-io.js';
+import {DidResolverError} from './DidResolverError.js';
+
+/**
+ * Determines if a DID contains URL characters and
+ * then validates either the DID URL or DID.
+ *
+ * @param {object} options - Options to use.
+ * @param {string} options.did - A DID.
+ *
+ * @throws {DidResolverError} Throws if DID is invalid.
+ *
+ * @returns {undefined} Returns on success.
+ */
+export function validateDid({did}) {
+  if(!did) {
+    throw new TypeError('The parameter "did" is required.');
+  }
+  if(isDidUrl({did})) {
+    if(!isValidDidUrl({didUrl: did})) {
+      throw new DidResolverError({
+        message: `Invalid DID URL "${did}"`,
+        code: 'invalidDidUrl'
+      });
+    }
+    return;
+  }
+  if(!isValidDid({did})) {
+    throw new DidResolverError({
+      message: `Invalid DID "${did}"`,
+      code: 'invalidDid'
+    });
+  }
+}
+
+/**
+ * Validates a DID, but not a DID URL.
+ * This function comes from the did-test-suite.
+ *
+ * @see https://github.com/w3c/did-test-suite/
+ *
+ * @param {object} options - Options to use.
+ * @param {string} options.did - A prospective DID.
+ *
+ * @returns {boolean} - Returns true if DID is valid.
+*/
+export function isValidDid({did}) {
+  const didRegex1 = new RegExp('^did:(?<method_name>[a-z0-9]+):' +
+  '(?<method_specific_id>([a-zA-Z0-9\\.\\-_]|%[0-9a-fA-F]{2}|:)+$)');
+  const didRegex2 = /:$/;
+  return didRegex1.test(did) && !didRegex2.test(did);
+}
+
+/**
+ * Validates a DID URL including the fragment and queries.
+ * This function comes from the did-test-suite.
+ *
+ * @see https://github.com/w3c/did-test-suite/
+ *
+ * @param {object} options - Options to use.
+ * @param {string} options.didUrl - A prospective DID URL.
+ *
+ * @returns {boolean} - Returns true or false.
+*/
+export function isValidDidUrl({didUrl}) {
+  const pchar = '[a-zA-Z0-9\\-\\._~]|%[0-9a-fA-F]{2}|[!$&\'()*+,;=:@]';
+  const didUrlPattern =
+      '^' +
+      'did:' +
+      '([a-z0-9]+)' + // method_name
+      '(:' + // method-specific-id
+          '([a-zA-Z0-9\\.\\-_]|%[0-9a-fA-F]{2})+' +
+      ')+' +
+      '((/(' + pchar + ')+)+)?' + // path-abempty
+      '(\\?(' + pchar + '|/|\\?)+)?' + // [ "?" query ]
+      '(#(' + pchar + '|/|\\?)+)?' + // [ "#" fragment ]
+      '$'
+      ;
+  return new RegExp(didUrlPattern).test(didUrl);
+}
diff --git a/test/did-io.spec.js b/test/01-did-io.spec.js
similarity index 93%
rename from test/did-io.spec.js
rename to test/01-did-io.spec.js
index 1bf81c6..6972223 100644
--- a/test/did-io.spec.js
+++ b/test/01-did-io.spec.js
@@ -17,9 +17,13 @@ const MOCK_KEY = {
 };
 
 describe('parseDid', () => {
-  it('should return main did method identifier', async () => {
-    const {prefix} = parseDid({did: 'did:v1:test:nym:abcd'});
-    expect(prefix).to.equal('v1');
+  it('should return did method', async () => {
+    const {method} = parseDid({did: 'did:v1:test:nym:abcd'});
+    expect(method).to.equal('v1');
+  });
+  it('should return did scheme', async () => {
+    const {scheme} = parseDid({did: 'did:v1:test:nym:abcd'});
+    expect(scheme).to.equal('did');
   });
 });
 
diff --git a/test/02-did-io-validators.spec.js b/test/02-did-io-validators.spec.js
new file mode 100644
index 0000000..4744c15
--- /dev/null
+++ b/test/02-did-io-validators.spec.js
@@ -0,0 +1,115 @@
+/*!
+ * Copyright (c) 2022 Digital Bazaar, Inc. All rights reserved.
+ */
+import chai from 'chai';
+import {testDid} from './helpers.js';
+import {isValidDid, isValidDidUrl} from '../lib/validators.js';
+import {DidResolverError} from '../lib/DidResolverError.js';
+import {
+  typeErrors,
+  invalidDids,
+  invalidDidSyntax,
+  invalidDidUrlSyntax,
+  invalidDidUrls,
+  validDids,
+  validDidUrls,
+} from './mock.data.js';
+
+const should = chai.should();
+
+describe('validateDid', () => {
+  describe('should not throw', () => {
+    const inputs = new Set([...validDids, ...validDidUrls]);
+    for(const input of inputs) {
+      it(`should validate ${input}`, async () => {
+        const error = testDid(input);
+        should.not.exist(error, `Expected no error for did ${input}`);
+      });
+    }
+  });
+  describe('should throw `TypeError`', () => {
+    for(const input of typeErrors) {
+      it(`should not validate ${input}`, async () => {
+        const error = testDid(input);
+        should.exist(error, `Expected error for did ${input}`);
+        error.should.be.instanceof(
+          TypeError,
+          `Expected a TypeError for ${input}`
+        );
+      });
+    }
+  });
+  describe('should throw `invalidDid`', () => {
+    const inputs = [...invalidDidSyntax, 'did:key:z4345345:'];
+    for(const input of inputs) {
+      it(`should not validate ${input}`, async () => {
+        const error = testDid(input);
+        should.exist(error, `Expected error for did ${input}`);
+        error.should.be.instanceof(
+          DidResolverError,
+          `Expected a DidResolverError for ${input}`
+        );
+        error.code.should.equal(
+          'invalidDid',
+          `Expected ${input} to be an invalid did.`
+        );
+      });
+    }
+  });
+  describe('should throw `invalidDidUrl`', () => {
+    for(const invalidDidUrl of invalidDidUrlSyntax) {
+      it(`should not validate ${invalidDidUrl}`, async () => {
+        const error = testDid(invalidDidUrl);
+        should.exist(error, `Expected error for did url ${invalidDidUrl}`);
+        error.should.be.instanceof(
+          DidResolverError,
+          `Expected a DidResolverError for ${invalidDidUrl}`
+        );
+        error.code.should.equal(
+          'invalidDidUrl',
+          `Expected ${invalidDidUrl} to be an invalid did url`
+        );
+      });
+    }
+  });
+});
+
+describe('isValidDidUrl', () => {
+  for(const validDidUrl of validDidUrls) {
+    it(`should validate ${validDidUrl}`, async () => {
+      const result = isValidDidUrl({didUrl: validDidUrl});
+      should.exist(result, `Expected result for ${validDidUrl} to exist.`);
+      result.should.be.a(
+        'boolean', 'Expected isValidDidUrl to return a boolean');
+      result.should.equal(true, `Expected ${validDidUrl} to validate`);
+    });
+  }
+  for(const invalidDidUrl of invalidDidUrls) {
+    it(`should not validate ${invalidDidUrl}`, async () => {
+      const result = isValidDidUrl({didUrl: invalidDidUrl});
+      should.exist(result, `Expected result for ${invalidDidUrl} to exist.`);
+      result.should.be.a(
+        'boolean', 'Expected isValidDidUrl to return a boolean');
+      result.should.equal(false, `Expected ${invalidDidUrl} to not validate`);
+    });
+  }
+});
+
+describe('isValidDid', () => {
+  for(const validDid of validDids) {
+    it(`should validate ${validDid}`, async () => {
+      const result = isValidDid({did: validDid});
+      should.exist(result, `Expected result for ${validDid} to exist.`);
+      result.should.be.a('boolean', 'Expected isValidDid to return a boolean');
+      result.should.equal(true, `Expected ${validDid} to validate`);
+    });
+  }
+  for(const invalidDid of invalidDids) {
+    it(`should not validate ${invalidDid}`, async () => {
+      const result = isValidDid({did: invalidDid});
+      should.exist(result, `Expected result for ${invalidDid} to exist.`);
+      result.should.be.a('boolean', 'Expected isValidDid to return a boolean');
+      result.should.equal(false, `Expected ${invalidDid} to not validate`);
+    });
+  }
+});
diff --git a/test/helpers.js b/test/helpers.js
new file mode 100644
index 0000000..988d8b2
--- /dev/null
+++ b/test/helpers.js
@@ -0,0 +1,12 @@
+/*!
+ * Copyright (c) 2022 Digital Bazaar, Inc. All rights reserved.
+ */
+import {validateDid} from '../lib/validators.js';
+
+export function testDid(did) {
+  try {
+    validateDid({did});
+  } catch(e) {
+    return e;
+  }
+}
diff --git a/test/mock.data.js b/test/mock.data.js
new file mode 100644
index 0000000..27b6cec
--- /dev/null
+++ b/test/mock.data.js
@@ -0,0 +1,64 @@
+// these come from the did test suite and are here to ensure
+// the RegExp ported over for dids and did urls behave as expected
+export const validDidUrls = [
+  'did:example:123',
+  'did:example:123456789abcdefghi',
+  'did:example:123#ZC2jXTO6t4R501bfCXv3RxarZyUbdP2w_psLwMuY6ec',
+  'did:example:123#keys-1',
+  'did:example:123456/path',
+  'did:example:123456/path/multiple/path',
+  'did:example:123456/1path/2multiple/3path',
+  'did:example:123456/1-path/2-multiple/3-path',
+  'did:example:123456/path%20with%20space',
+  'did:example:123456?versionId=1',
+  'did:example:123#public-key-0',
+  'did:example:123#sig_064bebcc',
+  'did:example:123?service=agent&relativeRef=/credentials#degree',
+  'did:example:abc:def-hij#klm',
+  'did:orb:bafkreiazah4qrybzyapmrmk2dhldz24vfmavethcrgcoq7qhic63zz55ru:EiAag4' +
+  'cmgxAE2isL5HG3mxjS7WRq4l-xyyTgULCAcEHQQQ#nMef0L2qNWVe8yt97ap0vH7kQK2oFdm4z' +
+  'kQkYL7ymOo'
+];
+
+export const typeErrors = [
+  false,
+  0,
+  undefined,
+  null,
+  NaN
+];
+
+export const invalidDidSyntax = [
+  'STRING',
+  'did:',
+  'did:example'
+];
+
+export const invalidDidUrlSyntax = [
+  'did:example:id/validPath/ invalid path /',
+  'did:example:id/validPath/^invalid^path^/'
+];
+
+export const invalidDidUrls = [
+  ...typeErrors,
+  ...invalidDidSyntax,
+  ...invalidDidUrlSyntax
+];
+
+export const validDids = [
+  'did:example:123',
+  'did:example:123456789abcdefghi',
+  'did:example:123456789-abcdefghi',
+  'did:example:123456789_abcdefghi',
+  'did:example:123456789%20abcdefghi',
+  'did:example:123abc:123456789abcdefghi',
+  'did:example:abc%00',
+  'did:example::::::abc:::123'
+];
+
+export const invalidDids = [
+  ...invalidDidUrls,
+  'did:example:123#ZC2jXTO6t4R501bfCXv3RxarZyUbdP2w_psLwMuY6ec',
+  'did:example:123#keys-1',
+  'did:example:abc:::'
+];