diff --git a/site_scons/binaries.py b/site_scons/binaries.py
new file mode 100644
index 0000000..b858376
--- /dev/null
+++ b/site_scons/binaries.py
@@ -0,0 +1,42 @@
+# files.py
+#
+# Utilities for working with files and paths in SCons.
+#
+# Eryn Wells <eryn@erynwells.me>
+
+import os
+
+
+def which(program):
+    '''
+    Given a program name, search the system environment's $PATH for a binary of
+    that name. If one exists, return its name. If not, return None. This
+    function will also use the system environment's $PATHEXT to find binaries
+    with appropriate extensions (i.e., .exe on Windows).
+    '''
+    is_executable = lambda path: (    os.path.exists(path)
+                                  and os.access(path, os.X_OK))
+
+    path, name = os.path.split(program)
+    if path:
+        if is_executable(program):
+            return program
+    else:
+        pathext = [''] + os.environ.get('PATHEXT', '').split(os.pathsep)
+        for path in os.environ.get('PATH', '').split(os.pathsep):
+            exe = os.path.join(path, program)
+            for ext in pathext:
+                candidate = exe + ext
+                if is_executable(candidate):
+                    return candidate
+    return None
+
+
+def first(binaries):
+    '''
+    Given a list of binaries, return the first one found.
+    '''
+    for binary in binaries:
+        if which(binary):
+            return binary
+    return None
diff --git a/site_scons/site_init.py b/site_scons/site_init.py
new file mode 100644
index 0000000..874833e
--- /dev/null
+++ b/site_scons/site_init.py
@@ -0,0 +1,51 @@
+# site_init.py
+#
+# This file is read before every SConstruct and SConscript. So, anything that
+# should be available to every build script should go here.
+#
+# Eryn Wells <eryn@erynwells.me>
+
+import os.path
+import SCons.Defaults
+import binaries
+
+
+BUILD_DIR = Dir('#build')
+LIB_DIR = Dir('#lib')
+SRC_DIR = Dir('#src')
+TEST_DIR = Dir('#test')
+
+#
+# SCons Command Line Options
+#
+
+AddOption('--show-build-cmds',
+          dest='build_cmds',
+          action='store_true',
+          help='Show build commands instead of friendly build messages')
+AddOption('--mode',
+          dest='mode',
+          metavar='MODE',
+          help='The build mode')
+
+#
+# Environment Configuration
+#
+
+def has_clang(env):
+    _, cc_tail = os.path.split(env['CC'])
+    _, cxx_tail = os.path.split(env['CXX'])
+    return any([cc_tail.startswith('clang'), cxx_tail.startswith('clang')])
+
+default_env = SCons.Defaults.DefaultEnvironment()
+default_env['CC'] = binaries.first(['clang', 'gcc'])
+default_env['CXX'] = binaries.first(['clang++', 'g++'])
+
+default_env.Append(CCFLAGS=['-Wall', '-Wextra', '-pedantic'])
+if has_clang(default_env):
+    # Only clang supports color.
+    default_env.Append(CCFLAGS=['-fcolor-diagnostics'])
+default_env.Append(CFLAGS=['-std=c99'])
+default_env.Append(CXXFLAGS=['-std=c++11'])
+
+