diff --git a/src/ContextInterface.php b/src/ContextInterface.php
index cbfdef6..d038059 100644
--- a/src/ContextInterface.php
+++ b/src/ContextInterface.php
@@ -1,7 +1,7 @@
 <?php
 namespace Icicle\Concurrent;
 
-interface ContextInterface extends Sync\ChannelInterface
+interface ContextInterface
 {
     /**
      * @return bool
diff --git a/src/Forking/Fork.php b/src/Forking/Fork.php
index c73c232..740008d 100644
--- a/src/Forking/Fork.php
+++ b/src/Forking/Fork.php
@@ -1,11 +1,11 @@
 <?php
 namespace Icicle\Concurrent\Forking;
 
-use Icicle\Concurrent\ContextInterface;
 use Icicle\Concurrent\Exception\ForkException;
 use Icicle\Concurrent\Exception\InvalidArgumentError;
 use Icicle\Concurrent\Exception\StatusError;
 use Icicle\Concurrent\Exception\SynchronizationError;
+use Icicle\Concurrent\ProcessInterface;
 use Icicle\Concurrent\Sync\Channel;
 use Icicle\Concurrent\Sync\ChannelInterface;
 use Icicle\Concurrent\Sync\Internal\ExitFailure;
@@ -19,7 +19,7 @@ use Icicle\Stream\Pipe\DuplexPipe;
 /**
  * Implements a UNIX-compatible context using forked processes.
  */
-class Fork implements ContextInterface
+class Fork implements ChannelInterface, ProcessInterface
 {
     /**
      * @var \Icicle\Concurrent\Sync\Channel A channel for communicating with the child.
@@ -255,6 +255,20 @@ class Fork implements ContextInterface
         $this->channel = null;
     }
 
+    /**
+     * @param int $signo
+     *
+     * @throws \Icicle\Concurrent\Exception\StatusError
+     */
+    public function signal($signo)
+    {
+        if (0 === $this->pid) {
+            throw new StatusError('The fork has not been started or has already finished.');
+        }
+
+        posix_kill($this->pid, (int) $signo);
+    }
+
     /**
      * @coroutine
      *
diff --git a/src/Process/ChannelledProcess.php b/src/Process/ChannelledProcess.php
index 044a524..d0cbfc4 100644
--- a/src/Process/ChannelledProcess.php
+++ b/src/Process/ChannelledProcess.php
@@ -1,14 +1,15 @@
 <?php
 namespace Icicle\Concurrent\Process;
 
-use Icicle\Concurrent\ContextInterface;
 use Icicle\Concurrent\Exception\InvalidArgumentError;
 use Icicle\Concurrent\Exception\StatusError;
 use Icicle\Concurrent\Exception\SynchronizationError;
+use Icicle\Concurrent\ProcessInterface;
 use Icicle\Concurrent\Sync\Channel;
+use Icicle\Concurrent\Sync\ChannelInterface;
 use Icicle\Concurrent\Sync\Internal\ExitStatusInterface;
 
-class ChannelledProcess implements ContextInterface
+class ChannelledProcess implements ChannelInterface, ProcessInterface
 {
     /**
      * @var \Icicle\Concurrent\Process\Process
@@ -125,4 +126,20 @@ class ChannelledProcess implements ContextInterface
         $this->process->kill();
         $this->channel = null;
     }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getPid()
+    {
+        return $this->process->getPid();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function signal($signo)
+    {
+        $this->process->signal($signo);
+    }
 }
diff --git a/src/Process/Process.php b/src/Process/Process.php
index 0721b88..e36d2ef 100644
--- a/src/Process/Process.php
+++ b/src/Process/Process.php
@@ -1,15 +1,15 @@
 <?php
 namespace Icicle\Concurrent\Process;
 
-use Exception;
 use Icicle\Concurrent\Exception\ProcessException;
 use Icicle\Concurrent\Exception\StatusError;
+use Icicle\Concurrent\ProcessInterface;
 use Icicle\Loop;
 use Icicle\Promise\Promise;
 use Icicle\Stream\Pipe\ReadablePipe;
 use Icicle\Stream\Pipe\WritablePipe;
 
-class Process
+class Process implements ProcessInterface
 {
     /**
      * @var resource|null
diff --git a/src/ProcessInterface.php b/src/ProcessInterface.php
new file mode 100644
index 0000000..3a95520
--- /dev/null
+++ b/src/ProcessInterface.php
@@ -0,0 +1,17 @@
+<?php
+namespace Icicle\Concurrent;
+
+interface ProcessInterface extends ContextInterface
+{
+    /**
+     * @return int PID of process.
+     */
+    public function getPid();
+
+    /**
+     * @param int $signo
+     *
+     * @throws \Icicle\Concurrent\Exception\StatusError
+     */
+    public function signal($signo);
+}
diff --git a/src/Threading/Thread.php b/src/Threading/Thread.php
index 4603b74..0b7b627 100644
--- a/src/Threading/Thread.php
+++ b/src/Threading/Thread.php
@@ -7,6 +7,7 @@ use Icicle\Concurrent\Exception\StatusError;
 use Icicle\Concurrent\Exception\SynchronizationError;
 use Icicle\Concurrent\Exception\ThreadException;
 use Icicle\Concurrent\Sync\Channel;
+use Icicle\Concurrent\Sync\ChannelInterface;
 use Icicle\Concurrent\Sync\Internal\ExitStatusInterface;
 use Icicle\Coroutine;
 use Icicle\Stream;
@@ -19,7 +20,7 @@ use Icicle\Stream\Pipe\DuplexPipe;
  * maintained both in the context that creates the thread and in the thread
  * itself.
  */
-class Thread implements ContextInterface
+class Thread implements ChannelInterface, ContextInterface
 {
     const LATENCY_TIMEOUT = 0.01; // 10 ms