diff --git a/.travis.yml b/.travis.yml
index d474f41..f9a6516 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,21 +1,42 @@
 language: rust
 
+dist: trusty
+
+os:
+  - linux
+  - osx
+
+addons:
+  apt:
+    sources:
+      # Provides newer gcc.
+      - ubuntu-toolchain-r-test
+      # Provides libclang 3.9.
+      - llvm-toolchain-trusty-3.9
+    packages:
+      - autoconf2.13
+      # bindgen requires libclang >= 3.9.
+      - clang-3.9
+      # SpiderMonkey needs gcc >= 4.9 and 5 is ICEing.
+      - gcc-6
+      - g++-6
+
 rust:
-  - stable
-  - beta
   - nightly
 
 cache: cargo
 
 env:
   matrix:
-    - PROFILE="--release"
-    - PROFILE=""
+    - PROFILE="--release" FEATURES=""
+    - PROFILE=""          FEATURES=""
+    - PROFILE="--release" FEATURES="--features debugmozjs"
+    - PROFILE=""          FEATURES="--features debugmozjs"
 
+before_install:
+- source ./ci/before_install.sh
 
 script:
-  - cargo build $PROFILE --verbose
-  - cargo test $PROFILE --verbose
-  - if [[ "$PROFILE" == "--release" ]]; then
-        cargo bench;
-    fi
+  - ccache -z
+  - PROFILE="$PROFILE" FEATURES="$FEATURES" travis_wait ./ci/script.sh
+  - ccache --show-stats
diff --git a/Cargo.lock b/Cargo.lock
index 96342b7..70d2822 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,6 +2,9 @@
 name = "starling"
 version = "0.1.0"
 dependencies = [
+ "backtrace 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "clap 2.26.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "error-chain 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "js 0.1.4 (git+https://github.com/fitzgen/mozjs?branch=smup)",
  "tokio-core 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -38,6 +41,30 @@ dependencies = [
  "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "backtrace"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "backtrace-sys 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cfg-if 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cpp_demangle 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "dbghelp-sys 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.21 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-demangle 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "backtrace-sys"
+version = "0.1.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "gcc 0.3.51 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.21 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "bindgen"
 version = "0.26.3"
@@ -130,6 +157,24 @@ dependencies = [
  "gcc 0.3.51 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "cpp_demangle"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "fixedbitset 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "dbghelp-sys"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi-build 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "env_logger"
 version = "0.4.3"
@@ -139,6 +184,19 @@ dependencies = [
  "regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "error-chain"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "backtrace 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "fixedbitset"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "futures"
 version = "0.1.13"
@@ -363,6 +421,11 @@ name = "regex-syntax"
 version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "rustc-demangle"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "rustc-serialize"
 version = "0.3.24"
@@ -554,6 +617,8 @@ dependencies = [
 "checksum ansi_term 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "23ac7c30002a5accbf7e8987d0632fa6de155b7c3d39d0067317a391e00a2ef6"
 "checksum aster 0.41.0 (registry+https://github.com/rust-lang/crates.io-index)" = "4ccfdf7355d9db158df68f976ed030ab0f6578af811f5a7bb6dcf221ec24e0e0"
 "checksum atty 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "d912da0db7fa85514874458ca3651fe2cddace8d0b0505571dbdcd41ab490159"
+"checksum backtrace 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "72f9b4182546f4b04ebc4ab7f84948953a118bd6021a1b6a6c909e3e94f6be76"
+"checksum backtrace-sys 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)" = "afccc5772ba333abccdf60d55200fa3406f8c59dcf54d5f7998c9107d3799c7c"
 "checksum bindgen 0.26.3 (registry+https://github.com/rust-lang/crates.io-index)" = "c57d6c0f6e31f8dcf4d12720a3c2a9ffb70638772a5784976cf4fce52145f22a"
 "checksum bitflags 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)" = "1370e9fc2a6ae53aea8b7a5110edbd08836ed87c88736dfabccade1c2b44bff4"
 "checksum bitflags 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4efd02e230a02e18f92fc2735f44597385ed02ad8f831e7c1c1156ee5e1ab3a5"
@@ -564,7 +629,11 @@ dependencies = [
 "checksum clang-sys 0.19.0 (registry+https://github.com/rust-lang/crates.io-index)" = "611ec2e3a7623afd8a8c0d027887b6b55759d894abbf5fe11b9dc11b50d5b49a"
 "checksum clap 2.26.0 (registry+https://github.com/rust-lang/crates.io-index)" = "2267a8fdd4dce6956ba6649e130f62fb279026e5e84b92aa939ac8f85ce3f9f0"
 "checksum cmake 0.1.24 (registry+https://github.com/rust-lang/crates.io-index)" = "b8ebbb35d3dc9cd09497168f33de1acb79b265d350ab0ac34133b98f8509af1f"
+"checksum cpp_demangle 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)" = "7f374549b5aa87e566f17445e1aa17c86db0a8d19be7a72b2b1ac7bf5414df50"
+"checksum dbghelp-sys 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "97590ba53bcb8ac28279161ca943a924d1fd4a8fb3fa63302591647c4fc5b850"
 "checksum env_logger 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)" = "3ddf21e73e016298f5cb37d6ef8e8da8e39f91f9ec8b0df44b7deb16a9f8cd5b"
+"checksum error-chain 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d9435d864e017c3c6afeac1654189b06cdb491cf2ff73dbf0d73b0f292f42ff8"
+"checksum fixedbitset 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "b0cb3d75726fa0c5ed3dce5dfcf0796affa2a60b33967f45012d86fb95a886f2"
 "checksum futures 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "55f0008e13fc853f79ea8fc86e931486860d4c4c156cdffb59fa5f7fa833660a"
 "checksum gcc 0.3.51 (registry+https://github.com/rust-lang/crates.io-index)" = "120d07f202dcc3f72859422563522b66fe6463a4c513df062874daad05f85f0a"
 "checksum glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "8be18de09a56b60ed0edf84bc9df007e30040691af7acd1c41874faac5895bfb"
@@ -592,6 +661,7 @@ dependencies = [
 "checksum quasi_codegen 0.32.0 (registry+https://github.com/rust-lang/crates.io-index)" = "51b9e25fa23c044c1803f43ca59c98dac608976dd04ce799411edd58ece776d4"
 "checksum regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "1731164734096285ec2a5ec7fea5248ae2f5485b3feeb0115af4fda2183b2d1b"
 "checksum regex-syntax 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ad890a5eef7953f55427c50575c680c42841653abd2b028b68cd223d157f62db"
+"checksum rustc-demangle 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "3058a43ada2c2d0b92b3ae38007a2d0fa5e9db971be260e0171408a4ff471c95"
 "checksum rustc-serialize 0.3.24 (registry+https://github.com/rust-lang/crates.io-index)" = "dcf128d1287d2ea9d80910b5f1120d0b8eede3fbf1abe91c40d39ea7d51e6fda"
 "checksum scoped-tls 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f417c22df063e9450888a7561788e9bd46d3bb3c1466435b4eccb903807f147d"
 "checksum slab 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "17b4fcaed89ab08ef143da37bc52adbcc04d4a69014f4c1208d6b51f0c47bc23"
diff --git a/Cargo.toml b/Cargo.toml
index ff4a9c8..c2161fe 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,17 +1,31 @@
 [package]
-authors = ["Nick Fitzgerald <fitzgen@gmail.com>"]
+authors = ["The Starling Project Developers"]
+description = "The project that will henceforth be known as `starling`."
 name = "starling"
 version = "0.1.0"
-
 [[bin]]
+doc = false
 name = "starling"
 path = "src/bin/starling.rs"
-doc = false
+required-features = ["clap"]
 
 [dependencies]
+error-chain = "0.10.0"
 futures = "0.1.13"
 tokio-core = "0.1.6"
 
+[dependencies.clap]
+optional = true
+version = "2.26.0"
+
+[dependencies.backtrace]
+features = ["cpp_demangle"]
+version = "0.3.2"
+
 [dependencies.js]
-git = "https://github.com/fitzgen/mozjs"
 branch = "smup"
+git = "https://github.com/fitzgen/mozjs"
+
+[features]
+default = ["clap"]
+debugmozjs = ['js/debugmozjs']
diff --git a/ci/before_install.sh b/ci/before_install.sh
new file mode 100755
index 0000000..07626d4
--- /dev/null
+++ b/ci/before_install.sh
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+
+# We always want backtraces for everything.
+export RUST_BACKTRACE=1
+
+if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
+    brew install autoconf@2.13 ccache llvm@3.9 yasm
+    export LIBCLANG_PATH=$(find /usr/local/Cellar/llvm -type f -name libclang.dylib | head -n 1)
+    export LIBCLANG_PATH=$(dirname $LIBCLANG_PATH)
+elif [[ "$TRAVIS_OS_NAME" == "linux" ]]; then
+    export CC=clang-3.9
+    export CXX=clang++-3.9
+    export LIBCLANG_PATH=/usr/lib/llvm-3.9/lib
+else
+    echo "Error: unknown \$TRAVIS_OS_NAME: $TRAVIS_OS_NAME"
+    exit 1
+fi
+
+ccache -c
+export CCACHE=$(which ccache)
diff --git a/ci/script.sh b/ci/script.sh
new file mode 100755
index 0000000..c9139f4
--- /dev/null
+++ b/ci/script.sh
@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+set -eux
+
+cargo build -v $PROFILE $FEATURES
+cargo test -v $PROFILE $FEATURES
+
+if [[ "$PROFILE" == "--release" && "$FEATURES" == "" ]]; then
+    cargo bench -v
+fi
diff --git a/rustfmt.toml b/rustfmt.toml
new file mode 100644
index 0000000..4b90c54
--- /dev/null
+++ b/rustfmt.toml
@@ -0,0 +1,5 @@
+reorder_imports = true
+reorder_imported_names = true
+write_mode = "Overwrite"
+closure_block_indent_threshold = 0
+use_try_shorthand = true
diff --git a/src/bin/starling.rs b/src/bin/starling.rs
index 268a99d..d7397bb 100644
--- a/src/bin/starling.rs
+++ b/src/bin/starling.rs
@@ -1,10 +1,37 @@
+extern crate clap;
+extern crate error_chain;
 extern crate starling;
 
+use clap::{App, Arg};
+use error_chain::ChainedError;
 use std::process;
 
+/// Parse the given CLI arguments into a `starling::Options` configuration
+/// object.
+///
+/// If argument parsing fails, then a usage string is printed, and the process
+/// is exited with 1.
+fn parse_cli_args() -> starling::Options {
+    let matches = App::new(env!("CARGO_PKG_NAME"))
+        .version(env!("CARGO_PKG_VERSION"))
+        .author(env!("CARGO_PKG_AUTHORS"))
+        .about(env!("CARGO_PKG_DESCRIPTION"))
+        .arg(
+            Arg::with_name("file")
+                .required(true)
+                .help("The JavaScript file to evaluate as the main task."),
+        )
+        .get_matches();
+
+    let opts = starling::Options::new(matches.value_of("file").unwrap());
+
+    opts
+}
+
 fn main() {
-    if let Err(e) = starling::run() {
-        println!("Error: {}", e);
+    let opts = parse_cli_args();
+    if let Err(e) = opts.run() {
+        println!("{}", e.display());
         process::exit(1);
     }
 }
diff --git a/src/lib.rs b/src/lib.rs
index ec9b0f6..dbeac9f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,21 +1,74 @@
 //! The project that will henceforth be known as `starling`.
-
+//!
+// `error_chain!` can recurse deeply
+#![recursion_limit = "1024"]
 #![deny(missing_docs)]
 #![deny(missing_debug_implementations)]
+#![deny(unsafe_code)]
+// Annoying warning emitted from the `error_chain!` macro.
+#![allow(unused_doc_comment)]
 
+#[macro_use]
+extern crate error_chain;
 extern crate futures;
 extern crate tokio_core;
 
 use futures::future;
-use std::io;
+use std::path;
 use tokio_core::reactor::Core;
 
-/// Run the main `starling` loop.
-pub fn run() -> Result<(), io::Error> {
+error_chain! {
+    foreign_links {
+        Io(::std::io::Error)
+        /// An IO error.
+            ;
+    }
+}
+
+/// Configuration options for building a `starling` event loop.
+///
+/// ```
+/// extern crate starling;
+///
+/// # fn foo() -> starling::Result<()> {
+/// // Construct a new `Options` builder, providing the file containing
+/// // the main JavaScript task.
+/// starling::Options::new("path/to/main.js")
+///     // Finish configuring the `Options` builder and run the event
+///     // loop!
+///     .run()?;
+/// # Ok(())
+/// # }
+/// ```
+#[derive(Clone, Debug)]
+pub struct Options {
+    main: path::PathBuf,
+}
+
+impl Options {
+    /// Construct a new `Options` object for configuring the `starling` event
+    /// loop.
+    ///
+    /// The given `main` JavaScript file will be evaluated as the main task.
+    pub fn new<P>(main: P) -> Options
+    where
+        P: Into<path::PathBuf>,
+    {
+        Options { main: main.into() }
+    }
+
+    /// Finish this `Options` builder and run the `starling` event loop with its
+    /// specified configuration.
+    pub fn run(self) -> Result<()> {
+        run_with_options(self)
+    }
+}
+
+/// Run the main `starling` event loop with the specified options.
+fn run_with_options(_opts: Options) -> Result<()> {
     let mut core = Core::new()?;
     core.run(future::ok(()))
 }
 
 #[test]
-fn it_works() {
-}
+fn it_works() {}