diff --git a/src/Handler.php b/src/Handler.php
index d04abf7c..3b94cde5 100644
--- a/src/Handler.php
+++ b/src/Handler.php
@@ -11,24 +11,85 @@ class Handler
      */
     protected $client;
 
+    /**
+     * The previously registered error handler as returned by the interpreter.
+     *
+     * @var callable|null
+     */
+    protected $previousErrorHandler;
+
+    /**
+     * The previously registered exception handler as returned by the interpreter.
+     *
+     * @var callable|null
+     */
+    protected $previousExceptionHandler;
+
     /**
      * Register our exception handler.
      *
      * @param \Bugsnag\Client|string|null $client client instance or api key
+     * @param bool $callPrevious whether or not to call the previous handlers
      *
      * @return static
      */
-    public static function register($client = null)
+    public static function register($client = null, $callPrevious = true)
     {
         $handler = new static($client instanceof Client ? $client : Client::make($client));
 
-        set_error_handler([$handler, 'errorHandler']);
-        set_exception_handler([$handler, 'exceptionHandler']);
-        register_shutdown_function([$handler, 'shutdownHandler']);
+        $handler->registerErrorHandler($callPrevious);
+        $handler->registerExceptionHandler($callPrevious);
+        $handler->registerShutdownHandler();
 
         return $handler;
     }
 
+    /**
+     * Register the bugsnag error handler and save the previous one
+     * (if it exists) to call later.
+     *
+     * @param bool $callPrevious whether or not to call the previous handler
+     *
+     * @return void
+     */
+    public function registerErrorHandler($callPrevious = true)
+    {
+        $previous = set_error_handler([$this, 'errorHandler']);
+
+        if ($callPrevious) {
+            $this->previousErrorHandler = $previous;
+        }
+    }
+
+    /**
+     * Register the bugsnag exception handler and save the previous one
+     * (if it exists) to call later.
+     *
+     * @param bool $callPrevious whether or not to call the previous handler
+     *
+     * @return void
+     */
+    public function registerExceptionHandler($callPrevious = true)
+    {
+        $previous = set_exception_handler([$this, 'exceptionHandler']);
+
+        if ($callPrevious) {
+            $this->previousExceptionHandler = $previous;
+        }
+    }
+
+    /**
+     * Register our shutdown handler.
+     *
+     * PHP will call shutdown functions in the order they were registered.
+     *
+     * @return void
+     */
+    public function registerShutdownHandler()
+    {
+        register_shutdown_function([$this, 'shutdownHandler']);
+    }
+
     /**
      * Create a new exception handler instance.
      *
@@ -55,6 +116,13 @@ public function exceptionHandler($throwable)
         $report->setSeverity('error');
 
         $this->client->notify($report);
+
+        if ($this->previousExceptionHandler) {
+            call_user_func(
+                $this->previousExceptionHandler,
+                $throwable
+            );
+        }
     }
 
     /**
@@ -69,15 +137,23 @@ public function exceptionHandler($throwable)
      */
     public function errorHandler($errno, $errstr, $errfile = '', $errline = 0)
     {
-        if ($this->client->shouldIgnoreErrorCode($errno)) {
-            return;
-        }
+        if (!$this->client->shouldIgnoreErrorCode($errno)) {
+            $report = Report::fromPHPError($this->client->getConfig(), $errno, $errstr, $errfile, $errline);
 
-        $report = Report::fromPHPError($this->client->getConfig(), $errno, $errstr, $errfile, $errline);
-
-        $this->client->notify($report);
+            $this->client->notify($report);
+        }
 
-        return false;
+        if ($this->previousErrorHandler) {
+            call_user_func(
+                $this->previousErrorHandler,
+                $errno,
+                $errstr,
+                $errfile,
+                $errline
+            );
+        } else {
+            return false;
+        }
     }
 
     /**
diff --git a/tests/HandlerTest.php b/tests/HandlerTest.php
index 0ef43c7c..d1fb0233 100644
--- a/tests/HandlerTest.php
+++ b/tests/HandlerTest.php
@@ -31,6 +31,19 @@ public function testErrorHandler()
         Handler::register($this->client)->errorHandler(E_WARNING, 'Something broke', 'somefile.php', 123);
     }
 
+    public function testErrorHandlerPreviousOff()
+    {
+        // PHPUnit's error handler should not get called, so no exception should be raised.
+        $exception_raised = false;
+        try {
+            Handler::register($this->client, false)->errorHandler(E_WARNING, 'Something broke', 'somefile.php', 123);
+        } catch (\PHPUnit_Framework_Error_Warning $e) {
+            $exception_raised = true;
+        }
+
+        $this->assertFalse($exception_raised);
+    }
+
     public function testExceptionHandler()
     {
         $this->client->expects($this->once())->method('notify');
@@ -56,8 +69,23 @@ function ($e) use (&$previous_exception_handler_arg) {
         $this->assertSame($e_to_throw, $previous_exception_handler_arg);
     }
 
+    public function testExceptionHandlerCallsPreviousOff()
+    {
+        $previous_exception_handler_called = false;
+        set_exception_handler(
+            function ($e) use (&$previous_exception_handler_called) {
+                $previous_exception_handler_called = true;
+            }
+        );
+
+        Handler::register($this->client, false)->exceptionHandler(new Exception());
+
+        $this->assertFalse($previous_exception_handler_called);
+    }
+
     public function testErrorReportingLevel()
     {
+        $this->expectException(\PHPUnit_Framework_Error_Notice::class);
         $this->client->expects($this->once())->method('notify');
 
         $this->client->setErrorReportingLevel(E_NOTICE);
@@ -67,6 +95,7 @@ public function testErrorReportingLevel()
 
     public function testErrorReportingLevelFails()
     {
+        $this->expectException(\PHPUnit_Framework_Error_Warning::class);
         $this->client->expects($this->never())->method('notify');
 
         $this->client->setErrorReportingLevel(E_NOTICE);
@@ -76,6 +105,7 @@ public function testErrorReportingLevelFails()
 
     public function testErrorReportingWithoutNotice()
     {
+        $this->expectException(\PHPUnit_Framework_Error_Notice::class);
         $this->client->expects($this->never())->method('notify');
 
         $this->client->setErrorReportingLevel(E_ALL & ~E_NOTICE);