diff --git a/lib/initializer.js b/lib/initializer.js
index 9c6b45e..4dae138 100644
--- a/lib/initializer.js
+++ b/lib/initializer.js
@@ -31,6 +31,11 @@ module.exports = function Initializer(type, opts) {
     mod = Registry.findBy(type, opts[type]);
   }
 
+  if (!mod) {
+    var err = [ "Unable to find", type, "for", opts[type] ].join(" ");
+    throw new Error(err);
+  }
+
   var obj = mod[type](opts);
 
   _.each(obj, function(prop, name) {
diff --git a/spec/lib/initializer.spec.js b/spec/lib/initializer.spec.js
new file mode 100644
index 0000000..69f4eef
--- /dev/null
+++ b/spec/lib/initializer.spec.js
@@ -0,0 +1,101 @@
+"use strict";
+
+var initializer = lib("initializer"),
+    Registry = lib("registry"),
+    Config = lib("config");
+
+var Loopback = lib("test/loopback"),
+    Ping = lib("test/ping"),
+    TestAdaptor = lib("test/test-adaptor"),
+    TestDriver = lib("test/test-driver");
+
+describe("Initializer", function() {
+  beforeEach(function() {
+    spy(Registry, "findBy");
+    stub(Registry, "register");
+  });
+
+  afterEach(function() {
+    Registry.findBy.restore();
+    Registry.register.restore();
+  });
+
+  it("creates an instance of the requested adaptor/driver", function() {
+    var adaptor = initializer("adaptor", { adaptor: "loopback" });
+    expect(adaptor).to.be.an.instanceOf(Loopback);
+
+    var driver = initializer("driver", { driver: "ping" });
+    expect(driver).to.be.an.instanceOf(Ping);
+  });
+
+  context("if the module isn't registered", function() {
+    var module;
+
+    beforeEach(function() {
+      Registry.findBy.restore();
+
+      module = {
+        adaptor: stub(),
+        driver: stub()
+      };
+
+      stub(Registry, "findBy")
+        .onFirstCall().returns(false)
+        .onSecondCall().returns(module);
+    });
+
+    context("if a module key was provided", function() {
+      it("attempts to register it", function() {
+        initializer("adaptor", { adaptor: "adaptor", module: "test" });
+        expect(Registry.register).to.be.calledWith("test");
+        expect(module.adaptor).to.be.called;
+      });
+    });
+
+    context("if no module key was provided", function() {
+      it("attempts to find it automatically", function() {
+        initializer("driver", { driver: "driver" });
+        expect(Registry.register).to.be.calledWith("cylon-driver");
+        expect(module.driver).to.be.called;
+      });
+    });
+
+    context("if the module still can't be found", function() {
+      beforeEach(function() {
+        Registry.findBy.onSecondCall().returns(false);
+      });
+
+      it("throws an error", function() {
+        function fn() {
+          return initializer("adaptor", { adaptor: "badadaptor" });
+        }
+
+        expect(fn).to.throw("Unable to find adaptor for badadaptor");
+      });
+    });
+  });
+
+  context("if in test mode", function() {
+    var tm = Config.testMode, adaptor, driver;
+
+    beforeEach(function() {
+      Config.testMode = true;
+
+      driver = initializer("driver", { driver: "ping" });
+      adaptor = initializer("adaptor", { adaptor: "loopback" });
+    });
+
+    afterEach(function() {
+      Config.testMode = tm;
+    });
+
+    it("creates a test adaptor/driver", function() {
+      expect(driver).to.be.an.instanceOf(TestDriver);
+      expect(adaptor).to.be.an.instanceOf(TestAdaptor);
+    });
+
+    it("stubs out the driver/adaptor behaviour", function() {
+      expect(driver.ping).to.be.a("function");
+    });
+  });
+});