diff --git a/Cargo.lock b/Cargo.lock
index e8714c13..f7207b6a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,3 +1,5 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
 [[package]]
 name = "aho-corasick"
 version = "0.6.6"
diff --git a/src/cmd/exclude.rs b/src/cmd/exclude.rs
new file mode 100644
index 00000000..3868e9c8
--- /dev/null
+++ b/src/cmd/exclude.rs
@@ -0,0 +1,267 @@
+use std::collections::hash_map::{Entry, HashMap};
+use std::fmt;
+use std::fs;
+use std::io;
+use std::str;
+
+use byteorder::{BigEndian, WriteBytesExt};
+use csv;
+
+use config::{Config, Delimiter};
+use index::Indexed;
+use select::{SelectColumns, Selection};
+use util;
+use CliResult;
+
+static USAGE: &'static str = "
+Removes a set of CSV data from another set based on the specified columns.
+
+Also can compute the intersection of two CSV sets with the -v flag.
+
+Matching is always done by ignoring leading and trailing whitespace. By default,
+matching is done case sensitively, but this can be disabled with the --no-case
+flag.
+
+The columns arguments specify the columns to match for each input. Columns can
+be referenced by name or index, starting at 1. Specify multiple columns by
+separating them with a comma. Specify a range of columns with `-`. Both
+columns1 and columns2 must specify exactly the same number of columns.
+(See 'xsv select --help' for the full syntax.)
+
+Usage:
+    xsv exclude [options] <columns1> <input1> <columns2> <input2>
+    xsv exclude --help
+
+join options:
+    --no-case              When set, matching is done case insensitively.
+    -v                     When set, matching rows will be the only ones included,
+                           forming set intersection, instead of the ones discarded.
+
+Common options:
+    -h, --help             Display this message
+    -o, --output <file>    Write output to <file> instead of stdout.
+    -n, --no-headers       When set, the first row will not be interpreted
+                           as headers. (i.e., They are not searched, analyzed,
+                           sliced, etc.)
+    -d, --delimiter <arg>  The field delimiter for reading CSV data.
+                           Must be a single character. (default: ,)
+";
+
+type ByteString = Vec<u8>;
+
+#[derive(Deserialize)]
+struct Args {
+    arg_columns1: SelectColumns,
+    arg_input1: String,
+    arg_columns2: SelectColumns,
+    arg_input2: String,
+    flag_v: bool,
+    flag_output: Option<String>,
+    flag_no_headers: bool,
+    flag_no_case: bool,
+    flag_delimiter: Option<Delimiter>,
+}
+
+pub fn run(argv: &[&str]) -> CliResult<()> {
+    let args: Args = util::get_args(USAGE, argv)?;
+    let mut state = args.new_io_state()?;
+    state.write_headers()?;
+    state.exclude(args.flag_v)
+}
+
+struct IoState<R, W: io::Write> {
+    wtr: csv::Writer<W>,
+    rdr1: csv::Reader<R>,
+    sel1: Selection,
+    rdr2: csv::Reader<R>,
+    sel2: Selection,
+    no_headers: bool,
+    casei: bool,
+}
+
+impl<R: io::Read + io::Seek, W: io::Write> IoState<R, W> {
+    fn write_headers(&mut self) -> CliResult<()> {
+        if !self.no_headers {
+            let mut headers = self.rdr1.byte_headers()?.clone();
+            self.wtr.write_record(&headers)?;
+        }
+        Ok(())
+    }
+
+    fn exclude(mut self, invert: bool) -> CliResult<()> {
+        let mut scratch = csv::ByteRecord::new();
+        let mut validx = ValueIndex::new(self.rdr2, &self.sel2, self.casei)?;
+        for row in self.rdr1.byte_records() {
+            let row = row?;
+            let key = get_row_key(&self.sel1, &row, self.casei);
+            match validx.values.get(&key) {
+                None => {
+                    if !invert {
+                        self.wtr.write_record(row.iter())?;
+                    } else {
+                        continue;
+                    }
+                }
+                Some(rows) => {
+                    if invert {
+                        self.wtr.write_record(row.iter())?;
+                    } else {
+                        continue;
+                    }
+                }
+            }
+        }
+        Ok(())
+    }
+}
+
+impl Args {
+    fn new_io_state(&self) -> CliResult<IoState<fs::File, Box<io::Write + 'static>>> {
+        let rconf1 = Config::new(&Some(self.arg_input1.clone()))
+            .delimiter(self.flag_delimiter)
+            .no_headers(self.flag_no_headers)
+            .select(self.arg_columns1.clone());
+        let rconf2 = Config::new(&Some(self.arg_input2.clone()))
+            .delimiter(self.flag_delimiter)
+            .no_headers(self.flag_no_headers)
+            .select(self.arg_columns2.clone());
+
+        let mut rdr1 = rconf1.reader_file()?;
+        let mut rdr2 = rconf2.reader_file()?;
+        let (sel1, sel2) = self.get_selections(&rconf1, &mut rdr1, &rconf2, &mut rdr2)?;
+        Ok(IoState {
+            wtr: Config::new(&self.flag_output).writer()?,
+            rdr1: rdr1,
+            sel1: sel1,
+            rdr2: rdr2,
+            sel2: sel2,
+            no_headers: rconf1.no_headers,
+            casei: self.flag_no_case,
+        })
+    }
+
+    fn get_selections<R: io::Read>(
+        &self,
+        rconf1: &Config,
+        rdr1: &mut csv::Reader<R>,
+        rconf2: &Config,
+        rdr2: &mut csv::Reader<R>,
+    ) -> CliResult<(Selection, Selection)> {
+        let headers1 = rdr1.byte_headers()?;
+        let headers2 = rdr2.byte_headers()?;
+        let select1 = rconf1.selection(&*headers1)?;
+        let select2 = rconf2.selection(&*headers2)?;
+        if select1.len() != select2.len() {
+            return fail!(format!(
+                "Column selections must have the same number of columns, \
+                 but found column selections with {} and {} columns.",
+                select1.len(),
+                select2.len()
+            ));
+        }
+        Ok((select1, select2))
+    }
+}
+
+struct ValueIndex<R> {
+    // This maps tuples of values to corresponding rows.
+    values: HashMap<Vec<ByteString>, Vec<usize>>,
+    idx: Indexed<R, io::Cursor<Vec<u8>>>,
+    num_rows: usize,
+}
+
+impl<R: io::Read + io::Seek> ValueIndex<R> {
+    fn new(mut rdr: csv::Reader<R>, sel: &Selection, casei: bool) -> CliResult<ValueIndex<R>> {
+        let mut val_idx = HashMap::with_capacity(10000);
+        let mut row_idx = io::Cursor::new(Vec::with_capacity(8 * 10000));
+        let (mut rowi, mut count) = (0usize, 0usize);
+
+        // This logic is kind of tricky. Basically, we want to include
+        // the header row in the line index (because that's what csv::index
+        // does), but we don't want to include header values in the ValueIndex.
+        if !rdr.has_headers() {
+            // ... so if there are no headers, we seek to the beginning and
+            // index everything.
+            let mut pos = csv::Position::new();
+            pos.set_byte(0);
+            rdr.seek(pos)?;
+        } else {
+            // ... and if there are headers, we make sure that we've parsed
+            // them, and write the offset of the header row to the index.
+            rdr.byte_headers()?;
+            row_idx.write_u64::<BigEndian>(0)?;
+            count += 1;
+        }
+
+        let mut row = csv::ByteRecord::new();
+        while rdr.read_byte_record(&mut row)? {
+            // This is a bit hokey. We're doing this manually instead of using
+            // the `csv-index` crate directly so that we can create both
+            // indexes in one pass.
+            row_idx.write_u64::<BigEndian>(row.position().unwrap().byte())?;
+
+            let fields: Vec<_> = sel.select(&row).map(|v| transform(v, casei)).collect();
+            if !fields.iter().any(|f| f.is_empty()) {
+                match val_idx.entry(fields) {
+                    Entry::Vacant(v) => {
+                        let mut rows = Vec::with_capacity(4);
+                        rows.push(rowi);
+                        v.insert(rows);
+                    }
+                    Entry::Occupied(mut v) => {
+                        v.get_mut().push(rowi);
+                    }
+                }
+            }
+            rowi += 1;
+            count += 1;
+        }
+
+        row_idx.write_u64::<BigEndian>(count as u64)?;
+        let idx = Indexed::open(rdr, io::Cursor::new(row_idx.into_inner()))?;
+        Ok(ValueIndex {
+            values: val_idx,
+            idx: idx,
+            num_rows: rowi,
+        })
+    }
+}
+
+impl<R> fmt::Debug for ValueIndex<R> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        // Sort the values by order of first appearance.
+        let mut kvs = self.values.iter().collect::<Vec<_>>();
+        kvs.sort_by(|&(_, v1), &(_, v2)| v1[0].cmp(&v2[0]));
+        for (keys, rows) in kvs.into_iter() {
+            // This is just for debugging, so assume Unicode for now.
+            let keys = keys
+                .iter()
+                .map(|k| String::from_utf8(k.to_vec()).unwrap())
+                .collect::<Vec<_>>();
+            writeln!(f, "({}) => {:?}", keys.join(", "), rows)?
+        }
+        Ok(())
+    }
+}
+
+fn get_row_key(sel: &Selection, row: &csv::ByteRecord, casei: bool) -> Vec<ByteString> {
+    sel.select(row).map(|v| transform(&v, casei)).collect()
+}
+
+fn transform(bs: &[u8], casei: bool) -> ByteString {
+    match str::from_utf8(bs) {
+        Err(_) => bs.to_vec(),
+        Ok(s) => {
+            if !casei {
+                s.trim().as_bytes().to_vec()
+            } else {
+                let norm: String = s
+                    .trim()
+                    .chars()
+                    .map(|c| c.to_lowercase().next().unwrap())
+                    .collect();
+                norm.into_bytes()
+            }
+        }
+    }
+}
diff --git a/src/cmd/mod.rs b/src/cmd/mod.rs
index 921ad00b..3dea92d5 100644
--- a/src/cmd/mod.rs
+++ b/src/cmd/mod.rs
@@ -1,5 +1,6 @@
 pub mod cat;
 pub mod count;
+pub mod exclude;
 pub mod fixlengths;
 pub mod flatten;
 pub mod fmt;
diff --git a/src/main.rs b/src/main.rs
index 0f9cacfe..1cda8bc8 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -45,6 +45,7 @@ macro_rules! command_list {
 "
     cat         Concatenate by row or column
     count       Count records
+    exclude     Excludes the records in one CSV from another
     fixlengths  Makes all records have same length
     flatten     Show one field per line
     fmt         Format CSV output (change field delimiter)
@@ -142,6 +143,7 @@ Please choose one of the following commands:",
 enum Command {
     Cat,
     Count,
+    Exclude,
     FixLengths,
     Flatten,
     Fmt,
@@ -177,6 +179,7 @@ impl Command {
         match self {
             Command::Cat => cmd::cat::run(argv),
             Command::Count => cmd::count::run(argv),
+            Command::Exclude => cmd::exclude::run(argv),
             Command::FixLengths => cmd::fixlengths::run(argv),
             Command::Flatten => cmd::flatten::run(argv),
             Command::Fmt => cmd::fmt::run(argv),
diff --git a/tests/test_exclude.rs b/tests/test_exclude.rs
new file mode 100644
index 00000000..27172359
--- /dev/null
+++ b/tests/test_exclude.rs
@@ -0,0 +1,87 @@
+use workdir::Workdir;
+
+// This macro takes *two* identifiers: one for the test with headers
+// and another for the test without headers.
+macro_rules! exclude_test {
+    ($name:ident, $fun:expr) => {
+        mod $name {
+            use std::process;
+
+            use super::{make_rows, setup};
+            use workdir::Workdir;
+
+            #[test]
+            fn headers() {
+                let wrk = setup(stringify!($name), true);
+                let mut cmd = wrk.command("exclude");
+                cmd.args(&["city", "cities.csv", "city", "places.csv"]);
+                $fun(wrk, cmd, true);
+            }
+
+            #[test]
+            fn no_headers() {
+                let n = stringify!(concat_idents!($name, _no_headers));
+                let wrk = setup(n, false);
+                let mut cmd = wrk.command("exclude");
+                cmd.arg("--no-headers");
+                cmd.args(&["1", "cities.csv", "1", "places.csv"]);
+                $fun(wrk, cmd, false);
+            }
+        }
+    };
+}
+
+fn setup(name: &str, headers: bool) -> Workdir {
+    let mut cities = vec![
+        svec!["Boston", "MA"],
+        svec!["New York", "NY"],
+        svec!["San Francisco", "CA"],
+        svec!["Buffalo", "NY"],
+    ];
+    let mut places = vec![
+        svec!["Boston", "Logan Airport"],
+        svec!["Boston", "Boston Garden"],
+        svec!["Buffalo", "Ralph Wilson Stadium"],
+        svec!["Orlando", "Disney World"],
+    ];
+    if headers {
+        cities.insert(0, svec!["city", "state"]);
+    }
+    if headers {
+        places.insert(0, svec!["city", "place"]);
+    }
+
+    let wrk = Workdir::new(name);
+    wrk.create("cities.csv", cities);
+    wrk.create("places.csv", places);
+    wrk
+}
+
+fn make_rows(headers: bool, rows: Vec<Vec<String>>) -> Vec<Vec<String>> {
+    let mut all_rows = vec![];
+    if headers {
+        all_rows.push(svec!["city", "state"]);
+    }
+    all_rows.extend(rows.into_iter());
+    all_rows
+}
+
+exclude_test!(exclude, |wrk: Workdir,
+                        mut cmd: process::Command,
+                        headers: bool| {
+    let got: Vec<Vec<String>> = wrk.read_stdout(&mut cmd);
+    let expected = make_rows(
+        headers,
+        vec![svec!["New York", "NY"], svec!["San Francisco", "CA"]],
+    );
+    assert_eq!(got, expected);
+});
+
+exclude_test!(include, |wrk: Workdir,
+                        mut cmd: process::Command,
+                        headers: bool| {
+    cmd.arg("-v");
+    let got: Vec<Vec<String>> = wrk.read_stdout(&mut cmd);
+    let expected = make_rows(headers, vec![svec!["Boston", "MA"], svec!["Buffalo", "NY"]]);
+    assert_eq!(got, expected);
+});
diff --git a/tests/tests.rs b/tests/tests.rs
index 37966bc7..a21f7605 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -35,6 +35,7 @@ mod workdir;
 
 mod test_cat;
 mod test_count;
+mod test_exclude;
 mod test_fixlengths;
 mod test_flatten;
 mod test_fmt;