diff --git a/README.md b/README.md
index 1c32578..74dbbc9 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,9 @@ Contrary to other file readers or writers, it is capable of processing very larg
 
 ## Installation
 
-The Spout library can be installed directly from [Composer](https://getcomposer.org/).
+### Composer (recommended)
+
+Spout can be installed directly from [Composer](https://getcomposer.org/).
 
 Add "box/spout" as a dependency in your project's composer.json file:
 ```json
@@ -27,6 +29,19 @@ Then run the install command from Composer:
 php composer.phar install
 ```
 
+### Manual installation
+
+If you can't use Composer, no worries! You can still install Spout manually.
+
+> Before starting, make sure your system meets the [requirements](#requirements).
+
+1. Download the source code from the [Releases page](https://github.com/box/spout/releases)
+2. Extract the downloaded content into your project.
+3. Add this code to the top controller (index.php) or wherever it may be more appropriate:
+```php
+require_once '[PATH/TO]/src/Spout/Autoloader/autoload.php'; // don't forget to change the path!
+```
+
 
 ## Requirements
 
diff --git a/phpunit.xml b/phpunit.xml
index 01178da..fc6d657 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -17,6 +17,9 @@
     <filter>
         <whitelist>
             <directory suffix=".php">src/</directory>
+            <exclude>
+                <directory>src/Spout/Autoloader</directory>
+            </exclude>
         </whitelist>
     </filter>
 
diff --git a/src/Spout/Autoloader/Psr4Autoloader.php b/src/Spout/Autoloader/Psr4Autoloader.php
new file mode 100644
index 0000000..649a732
--- /dev/null
+++ b/src/Spout/Autoloader/Psr4Autoloader.php
@@ -0,0 +1,150 @@
+<?php
+
+namespace Box\Spout\Autoloader;
+
+/**
+ * Class Psr4Autoloader
+ * @see https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-4-autoloader-examples.md#class-example
+ *
+ * @package Box\Spout\Autoloader
+ */
+class Psr4Autoloader
+{
+    /**
+     * An associative array where the key is a namespace prefix and the value
+     * is an array of base directories for classes in that namespace.
+     *
+     * @var array
+     */
+    protected $prefixes = array();
+
+    /**
+     * Register loader with SPL autoloader stack.
+     *
+     * @return void
+     */
+    public function register()
+    {
+        spl_autoload_register(array($this, 'loadClass'));
+    }
+
+    /**
+     * Adds a base directory for a namespace prefix.
+     *
+     * @param string $prefix The namespace prefix.
+     * @param string $base_dir A base directory for class files in the
+     * namespace.
+     * @param bool $prepend If true, prepend the base directory to the stack
+     * instead of appending it; this causes it to be searched first rather
+     * than last.
+     * @return void
+     */
+    public function addNamespace($prefix, $base_dir, $prepend = false)
+    {
+        // normalize namespace prefix
+        $prefix = trim($prefix, '\\') . '\\';
+
+        // normalize the base directory with a trailing separator
+        $base_dir = rtrim($base_dir, DIRECTORY_SEPARATOR) . '/';
+
+        // initialize the namespace prefix array
+        if (isset($this->prefixes[$prefix]) === false) {
+            $this->prefixes[$prefix] = array();
+        }
+
+        // retain the base directory for the namespace prefix
+        if ($prepend) {
+            array_unshift($this->prefixes[$prefix], $base_dir);
+        } else {
+            array_push($this->prefixes[$prefix], $base_dir);
+        }
+    }
+
+    /**
+     * Loads the class file for a given class name.
+     *
+     * @param string $class The fully-qualified class name.
+     * @return mixed The mapped file name on success, or boolean false on
+     * failure.
+     */
+    public function loadClass($class)
+    {
+        // the current namespace prefix
+        $prefix = $class;
+
+        // work backwards through the namespace names of the fully-qualified
+        // class name to find a mapped file name
+        while (false !== $pos = strrpos($prefix, '\\')) {
+
+            // retain the trailing namespace separator in the prefix
+            $prefix = substr($class, 0, $pos + 1);
+
+            // the rest is the relative class name
+            $relative_class = substr($class, $pos + 1);
+
+            // try to load a mapped file for the prefix and relative class
+            $mapped_file = $this->loadMappedFile($prefix, $relative_class);
+            if ($mapped_file) {
+                return $mapped_file;
+            }
+
+            // remove the trailing namespace separator for the next iteration
+            // of strrpos()
+            $prefix = rtrim($prefix, '\\');
+        }
+
+        // never found a mapped file
+        return false;
+    }
+
+    /**
+     * Load the mapped file for a namespace prefix and relative class.
+     *
+     * @param string $prefix The namespace prefix.
+     * @param string $relative_class The relative class name.
+     * @return mixed Boolean false if no mapped file can be loaded, or the
+     * name of the mapped file that was loaded.
+     */
+    protected function loadMappedFile($prefix, $relative_class)
+    {
+        // are there any base directories for this namespace prefix?
+        if (isset($this->prefixes[$prefix]) === false) {
+            return false;
+        }
+
+        // look through base directories for this namespace prefix
+        foreach ($this->prefixes[$prefix] as $base_dir) {
+
+            // replace the namespace prefix with the base directory,
+            // replace namespace separators with directory separators
+            // in the relative class name, append with .php
+            $file = $base_dir
+                  . str_replace('\\', '/', $relative_class)
+                  . '.php';
+
+            // if the mapped file exists, require it
+            if ($this->requireFile($file)) {
+                // yes, we're done
+                return $file;
+            }
+        }
+
+        // never found it
+        return false;
+    }
+
+    /**
+     * If a file exists, require it from the file system.
+     *
+     * @param string $file The file to require.
+     * @return bool True if the file exists, false if not.
+     */
+    protected function requireFile($file)
+    {
+        if (file_exists($file)) {
+            require $file;
+            return true;
+        }
+        return false;
+    }
+}
diff --git a/src/Spout/Autoloader/autoload.php b/src/Spout/Autoloader/autoload.php
new file mode 100644
index 0000000..73ee519
--- /dev/null
+++ b/src/Spout/Autoloader/autoload.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Box\Spout\Autoloader;
+
+require_once 'Psr4Autoloader.php';
+
+/**
+ * @var string $srcBaseDirectory
+ * Full path to "src/Spout" which is what we want "Box\Spout" to map to.
+ */
+$srcBaseDirectory = dirname(dirname(__FILE__));
+
+$loader = new Psr4Autoloader();
+$loader->register();
+$loader->addNamespace('Box\Spout', $srcBaseDirectory);