diff --git a/README.md b/README.md
index e4b5e9f..6a3ab8d 100644
--- a/README.md
+++ b/README.md
@@ -80,6 +80,18 @@ When a user attempts to register a new account, and either their provided userna
 
 ## API
 
+A brief listing of the currently defined error types, for easier searching:
+
+* UniqueConstraintViolationError
+* ForeignKeyConstraintViolationError
+* NotNullConstraintViolationError
+* CheckConstraintViolationError
+* InvalidTypeError
+* EnumError
+* UndefinedColumnError
+
+The full documentation for each type is below.
+
 ### databaseError.rethrow(error)
 
 Rethrows a more useful error, where possible.
@@ -134,10 +146,17 @@ A `UniqueConstraintViolationError` will contain the following additional propert
 
 * __schema:__ The schema in which the violation occurred.
 * __table:__ The table in which the violation occurred.
-* __column:__ The column in which the violation occurred.
-* __value:__ The offending duplicate value.
+* For single-column `UNIQUE` constraints:
+    * __column:__ The column in which the violation occurred.
+    * __value:__ The offending duplicate value.
+* For multiple-column (composite) `UNIQUE` constraints:
+    * __columns:__ The columns in which the violation occurred, as an array.
+    * __values:__ The offending duplicate values, as an array.
+* __isComposite:__ Whether the `UNIQUE` constraint involves multiple columns. Boolean.
 * __constraint:__ The name of the `UNIQUE` constraint that is being violated.
 
+Note that the keys for composite `UNIQUE` constraints are __plural__, not singular. This is intentional, to provide a more predictable API.
+
 #### databaseError.ForeignKeyConstraintViolationError
 
 This error is thrown when a query violates a foreign key constraint. In practice, this means that there's an attempt to point a foreign key at a non-existent entry (usually in another table).
@@ -201,3 +220,13 @@ An `EnumError` will contain the following additional properties:
 * __enumType:__ The name of the ENUM type for which an invalid value was inserted.
 * __value:__ The value that caused the error.
 * __query:__ The query that caused the error. This query may contain placeholders or be incomplete, and so is intended purely for reference purposes.
+
+#### databaseError.UndefinedColumnError
+
+This error is thrown when a query attempts to store a value into a column that doesn't exist. A typical cause of this is forgetting to update the database schema after updating an application.
+
+An `UndefinedColumnError` will contain the following additional properties:
+
+* __table:__ The table in which the value was attempted to be inserted.
+* __table:__ The non-existent column in which the value was attempted to be inserted.
+* __query:__ The query that caused the type error. This query may contain placeholders or be incomplete, and so is intended purely for reference purposes.
diff --git a/src/errors/undefined-column.js b/src/errors/undefined-column.js
new file mode 100644
index 0000000..d40a286
--- /dev/null
+++ b/src/errors/undefined-column.js
@@ -0,0 +1,40 @@
+'use strict';
+
+const createError = require("create-error");
+const pgErrorCodes = require("pg-error-codes");
+
+const DatabaseError = require("../database-error.js");
+const getTable = require("../get-table");
+
+let UndefinedColumnError = createError(DatabaseError, "UndefinedColumnError");
+
+let messageRegex = /^(.+) - column "([^"]+)" of relation "([^"]+)" does not exist$/;
+
+module.exports = {
+    error: UndefinedColumnError,
+    errorName: "UndefinedColumnError",
+    check: function checkType(error) {
+        return (
+            // PostgreSQL (via `pg`):
+            (error.length != null && error.file != null && error.line != null && error.routine != null && error.code === "42703")
+        )
+    },
+    convert: function convertError(error) {
+        let messageMatch = messageRegex.exec(error.message);
+
+        if (messageMatch == null) {
+            throw new Error("Encountered unknown error format");
+        }
+
+        let [_, query, column, table] = messageMatch;
+
+        return new UndefinedColumnError(`The '${column}' column does not exist in the '${table}' table`, {
+            originalError: error,
+            pgCode: error.code,
+            code: pgErrorCodes[error.code],
+            query: query,
+            table: table,
+            column: column,
+        });
+    }
+};
diff --git a/src/errors/unique-constraint-violation.js b/src/errors/unique-constraint-violation.js
index 0c7845f..1466693 100644
--- a/src/errors/unique-constraint-violation.js
+++ b/src/errors/unique-constraint-violation.js
@@ -3,6 +3,7 @@
 const createError = require("create-error");
 const pgErrorCodes = require("pg-error-codes");
 const DatabaseError = require("../database-error.js");
+const splitValues = require("../split-values");
 
 let UniqueConstraintViolationError = createError(DatabaseError, "UniqueConstraintViolationError");
 
@@ -18,16 +19,39 @@ module.exports = {
         )
     },
     convert: function convertError(error) {
-        let [_, column, value] = detailsRegex.exec(error.detail);
+        let [_, columnValue, valueValue] = detailsRegex.exec(error.detail);
 
-        return new UniqueConstraintViolationError(`Value '${value}' already exists for column '${column}' in table '${error.table}'`, {
+        let column, columns, value, values, messageColumn, messageValue, isComposite;
+
+        if (columnValue.includes(",")) {
+            columns = splitValues(columnValue);
+            messageColumn = `columns ${columns.map(column => `'${column}'`).join(", ")}`;
+            isComposite = true;
+        } else {
+            column = columnValue;
+            messageColumn = `column '${column}'`;
+            isComposite = false;
+        }
+
+        if (valueValue.includes(",")) {
+            values = splitValues(valueValue);
+            messageValue = `Values ${values.map(value => `'${value}'`).join(", ")} already exist`;
+        } else {
+            value = valueValue;
+            messageValue = `Value '${value}' already exists`;
+        }
+
+        return new UniqueConstraintViolationError(`${messageValue} for ${messageColumn} in table '${error.table}'`, {
             originalError: error,
             pgCode: error.code,
             code: pgErrorCodes[error.code],
             schema: error.schema,
             table: error.table,
             column: column,
+            columns: columns,
             value: value,
+            values: values,
+            isComposite: isComposite,
             constraint: error.constraint
         });
     }
diff --git a/src/index.js b/src/index.js
index 6102480..f38b282 100644
--- a/src/index.js
+++ b/src/index.js
@@ -12,6 +12,7 @@ let handlers = [
 	require("./errors/foreign-key-constraint-violation"),
 	require("./errors/enum"),
 	require("./errors/invalid-type"),
+	require("./errors/undefined-column"),
 	require("./errors/not-null-constraint-violation"),
 ]
 
diff --git a/src/split-values.js b/src/split-values.js
new file mode 100644
index 0000000..b93ad45
--- /dev/null
+++ b/src/split-values.js
@@ -0,0 +1,5 @@
+'use strict';
+
+module.exports = function splitValues(values) {
+	return values.split(",").map(value => value.trim());
+};
diff --git a/test/create-tables/composite-unique-constraint-violation.js b/test/create-tables/composite-unique-constraint-violation.js
new file mode 100644
index 0000000..fcb06bd
--- /dev/null
+++ b/test/create-tables/composite-unique-constraint-violation.js
@@ -0,0 +1,16 @@
+'use strict';
+
+module.exports = {
+    up: function createUniqueConstraintViolationTable(knex, errorHandler) {
+        return knex.schema.createTable("composite_unique_constraint_violation", (table) => {
+            table.increments("id");
+            table.text("email");
+            table.text("username");
+            table.text("name");
+            table.unique(["email", "username"]);
+        }).catch(errorHandler);
+    },
+    down: function dropUniqueConstraintViolationTable(knex, errorHandler) {
+        return knex.schema.dropTable("composite_unique_constraint_violation").catch(errorHandler);
+    }
+};
diff --git a/test/create-tables/index.js b/test/create-tables/index.js
index 6c51f10..e109b1b 100644
--- a/test/create-tables/index.js
+++ b/test/create-tables/index.js
@@ -4,6 +4,7 @@ const Promise = require("bluebird");
 
 let tables = [
     require("./unique-constraint-violation"),
+    require("./composite-unique-constraint-violation"),
     require("./check-constraint-violation"),
     require("./foreign-key-constraint-violation"),
     require("./enum"),
diff --git a/test/testcase/composite-unique-constraint-violation.js b/test/testcase/composite-unique-constraint-violation.js
new file mode 100644
index 0000000..06df69a
--- /dev/null
+++ b/test/testcase/composite-unique-constraint-violation.js
@@ -0,0 +1,21 @@
+'use strict';
+
+module.exports = function attemptCompositeUniqueConstraintViolation(knex) {
+    return knex("composite_unique_constraint_violation").insert([{
+        email: "foo@bar.com",
+        username: "foo",
+        name: "Joe"
+    }, {
+        email: "baz@qux.com",
+        username: "bar",
+        name: "Jane"
+    }, {
+        email: "foo@bar.com",
+        username: "baz",
+        name: "Pete"
+    }, {
+        email: "foo@bar.com",
+        username: "foo",
+        name: "Jill"
+    }]).returning("*");
+};
diff --git a/test/testcase/undefined-column.js b/test/testcase/undefined-column.js
new file mode 100644
index 0000000..ba480aa
--- /dev/null
+++ b/test/testcase/undefined-column.js
@@ -0,0 +1,10 @@
+'use strict';
+
+module.exports = function attemptInvalidColumn(knex) {
+    return knex("invalid_type").insert([{
+        name: "Joe",
+        age: 29,
+        active: true,
+        nonexistentColumn: "Hello!"
+    }]).returning("*");
+};