diff --git a/colorize.js b/colorize.js
index 0186c6e..a053b39 100644
--- a/colorize.js
+++ b/colorize.js
@@ -65,6 +65,10 @@ class Colorizer {
       message = level;
     }
 
+    if (this.isColorDisabledByEnvVar()) {
+      return message;
+    }
+
     //
     // If the color for the level is just a string
     // then attempt to colorize the message with it.
@@ -104,6 +108,21 @@ class Colorizer {
 
     return info;
   }
+
+  isColorDisabledByEnvVar() {
+    // eslint-disable-next-line no-process-env
+    const NO_COLOR = process.env.NO_COLOR;
+    /**
+     * If the environment variable NO_COLOR is truthy, the style of the output
+     *  is automatically disabled.
+     */
+    const COLOR_DISABLED = NO_COLOR &&
+      NO_COLOR !== '0' &&
+      NO_COLOR !== 'false' &&
+      NO_COLOR !== 'undefined';
+
+    return COLOR_DISABLED;
+  }
 }
 
 /*
diff --git a/test/cli.test.js b/test/cli.test.js
index 734d892..ce6b1d7 100644
--- a/test/cli.test.js
+++ b/test/cli.test.js
@@ -14,6 +14,11 @@ const { LEVEL, MESSAGE } = require('triple-beam');
 describe('cli', () => {
   before(setupLevels);
 
+  beforeEach(() => {
+    // eslint-disable-next-line no-process-env
+    process.env.NO_COLOR = undefined;
+  });
+
   it('cli() (default) sets info[MESSAGE]', assumeFormatted(
     cli(),
     infoify({ level: 'info', message: 'whatever' }),
diff --git a/test/colorize.test.js b/test/colorize.test.js
index 7cd046b..1874a89 100644
--- a/test/colorize.test.js
+++ b/test/colorize.test.js
@@ -1,3 +1,4 @@
+/* eslint-disable no-process-env */
 'use strict';
 
 const assume = require('assume');
@@ -12,9 +13,14 @@ const {
   setupLevels
 } = require('./helpers');
 
+// eslint-disable-next-line max-statements
 describe('colorize', () => {
   before(setupLevels);
 
+  beforeEach(() => {
+    process.env.NO_COLOR = undefined;
+  });
+
   it('colorize() (default)', assumeFormatted(
     colorize(),
     infoify({ level: 'info', message: 'whatever' }),
@@ -26,6 +32,20 @@ describe('colorize', () => {
     }
   ));
 
+  it('colorize() (default) when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+    assumeFormatted(
+      colorize(),
+      infoify({ level: 'info', message: 'whatever' }),
+      info => {
+        assume(info.level).is.a('string');
+        assume(info.message).is.a('string');
+        assume(info.level).equals('info');
+        assume(info.message).equals('whatever');
+      }
+    );
+  });
+
   it('colorize({ level: true })', assumeFormatted(
     colorize({ level: true }),
     infoify({ level: 'info', message: 'whatever' }),
@@ -37,6 +57,20 @@ describe('colorize', () => {
     }
   ));
 
+  it('colorize({ level: true }) when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+    assumeFormatted(
+      colorize({ level: true }),
+      infoify({ level: 'info', message: 'whatever' }),
+      info => {
+        assume(info.level).is.a('string');
+        assume(info.message).is.a('string');
+        assume(info.level).equals('info');
+        assume(info.message).equals('whatever');
+      }
+    );
+  });
+
   it('colorize{ message: true })', assumeFormatted(
     colorize({ message: true }),
     infoify({ level: 'info', message: 'whatever' }),
@@ -48,6 +82,20 @@ describe('colorize', () => {
     }
   ));
 
+  it('colorize{ message: true }) when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+    assumeFormatted(
+      colorize({ message: true }),
+      infoify({ level: 'info', message: 'whatever' }),
+      info => {
+        assume(info.level).is.a('string');
+        assume(info.message).is.a('string');
+        assume(info.level).equals('info');
+        assume(info.message).equals('whatever');
+      }
+    );
+  });
+
   it('colorize({ level: true, message: true })', assumeFormatted(
     colorize({ level: true, message: true }),
     infoify({ level: 'info', message: 'whatever' }),
@@ -59,6 +107,20 @@ describe('colorize', () => {
     }
   ));
 
+  it('colorize({ level: true, message: true }) when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+    assumeFormatted(
+      colorize({ level: true, message: true }),
+      infoify({ level: 'info', message: 'whatever' }),
+      info => {
+        assume(info.level).is.a('string');
+        assume(info.message).is.a('string');
+        assume(info.level).equals('info');
+        assume(info.message).equals('whatever');
+      }
+    );
+  });
+
   it('colorize({ all: true })', assumeFormatted(
     colorize({ all: true }),
     infoify({ level: 'info', message: 'whatever' }),
@@ -70,6 +132,20 @@ describe('colorize', () => {
     }
   ));
 
+  it('colorize({ all: true }) when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+    assumeFormatted(
+      colorize({ all: true }),
+      infoify({ level: 'info', message: 'whatever' }),
+      info => {
+        assume(info.level).is.a('string');
+        assume(info.message).is.a('string');
+        assume(info.level).equals('info');
+        assume(info.message).equals('whatever');
+      }
+    );
+  });
+
   it('colorize({ all: true }) [custom message]', assumeFormatted(
     colorize({ all: true }),
     {
@@ -88,6 +164,27 @@ describe('colorize', () => {
     }
   ));
 
+  it('colorize({ all: true }) [custom message] when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+    assumeFormatted(
+      colorize({ all: true }),
+      {
+        level: 'info',
+        [LEVEL]: 'info',
+        message: 'whatever',
+        [MESSAGE]: '[info] whatever custom'
+      },
+      info => {
+        assume(info.level).is.a('string');
+        assume(info.message).is.a('string');
+        assume(info[LEVEL]).equals('info');
+        assume(info.level).equals('info');
+        assume(info.message).equals('whatever');
+        assume(info[MESSAGE]).equals('[info] whatever custom');
+      }
+    );
+  });
+
   it('colorizes when LEVEL !== level', assumeFormatted(
     colorize(),
     { [LEVEL]: 'info', level: 'INFO', message: 'whatever' },
@@ -97,6 +194,20 @@ describe('colorize', () => {
       assume(info.level).equals(colors.green('INFO'));
     }
   ));
+
+  it('colorizes when LEVEL !== level when NO_COLOR is enabled', () => {
+    process.env.NO_COLOR = 'true';
+
+    assumeFormatted(
+      colorize(),
+      { [LEVEL]: 'info', level: 'INFO', message: 'whatever' },
+      info => {
+        assume(info.level).is.a('string');
+        assume(info.message).is.a('string');
+        assume(info.level).equals('INFO');
+      }
+    );
+  });
 });
 
 describe('Colorizer', () => {
@@ -117,19 +228,46 @@ describe('Colorizer', () => {
     );
   });
 
+  it('Colorizer.addColors({ string: string }) when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+    Colorizer.addColors({ weird: 'cyan' });
+
+    assume(Colorizer.allColors).deep.equals(
+      Object.assign({}, expected, { weird: 'cyan' })
+    );
+  });
+
   it('Colorizer.addColors({ string: [Array] })', () => {
     Colorizer.addColors({ multiple: ['red', 'bold'] });
     assume(Colorizer.allColors.multiple).is.an('array');
     assume(Colorizer.allColors.multiple).deep.equals(['red', 'bold']);
   });
 
+  it('Colorizer.addColors({ string: [Array] }) when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+    Colorizer.addColors({ multiple: ['red', 'bold'] });
+    assume(Colorizer.allColors.multiple).is.an('array');
+    assume(Colorizer.allColors.multiple).deep.equals(['red', 'bold']);
+  });
+
   // eslint-disable-next-line no-useless-escape
   it('Colorizer.addColors({ string: "(\w+)/s(\w+)" })', () => {
     Colorizer.addColors({ delimited: 'blue underline' });
     assume(Colorizer.allColors.delimited).deep.equals(['blue', 'underline']);
   });
 
+  // eslint-disable-next-line no-useless-escape
+  it('Colorizer.addColors({ string: "(\w+)/s(\w+)" }) when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+    Colorizer.addColors({ delimited: 'blue underline' });
+    assume(Colorizer.allColors.delimited).deep.equals(['blue', 'underline']);
+  });
+
   describe('#colorize(LEVEL, level, message)', () => {
+    beforeEach(() => {
+      process.env.NO_COLOR = undefined;
+    });
+
     const instance = new Colorizer();
 
     it('colorize(level) [single color]', () => {
@@ -152,4 +290,32 @@ describe('Colorizer', () => {
       );
     });
   });
+
+  describe('#colorize(LEVEL, level, message) when NO_COLOR env var is enabled', () => {
+    beforeEach(() => {
+      process.env.NO_COLOR = 'true';
+    });
+
+    const instance = new Colorizer();
+
+    it('colorize(level) [single color]', () => {
+      assume(instance.colorize('weird', 'weird')).equals('weird');
+    });
+
+    it('colorize(level) [multiple colors]', () => {
+      assume(instance.colorize('multiple', 'multiple')).equals(
+        'multiple'
+      );
+    });
+
+    it('colorize(level, message) [single color]', () => {
+      assume(instance.colorize('weird', 'weird', 'message')).equals('message');
+    });
+
+    it('colorize(level, message) [multiple colors]', () => {
+      assume(instance.colorize('multiple', 'multiple', 'message')).equals(
+        'message'
+      );
+    });
+  });
 });
diff --git a/test/uncolorize.test.js b/test/uncolorize.test.js
index 52da897..206b33f 100644
--- a/test/uncolorize.test.js
+++ b/test/uncolorize.test.js
@@ -1,3 +1,4 @@
+/* eslint-disable no-process-env */
 'use strict';
 
 const assume = require('assume');
@@ -42,6 +43,10 @@ function addAndRemoveColors(opts = {}) {
 describe('uncolorize', () => {
   before(setupLevels);
 
+  beforeEach(() => {
+    process.env.NO_COLOR = undefined;
+  });
+
   it('uncolorize() (default) removes all colors', assumeFormatted(
     addAndRemoveColors(),
     infoify({ level: 'info', message: 'whatever' }),
@@ -83,6 +88,29 @@ describe('uncolorize', () => {
     }
   ));
 
+  it('same uncolorize() (default) preserves mutable level formatting when NO_COLOR env var is enabled', () => {
+    process.env.NO_COLOR = 'true';
+
+    assumeFormatted(
+      combine(
+        format(info => {
+          info.level = info.level.toUpperCase();
+          return info;
+        })(),
+        colorize(),
+        uncolorize()
+      ),
+      { [LEVEL]: 'info', level: 'info', message: 'whatever' },
+      info => {
+        assume(info.level).is.a('string');
+        assume(info.message).is.a('string');
+
+        assume(info.level).equals('INFO');
+        assume(info.message).equals('whatever');
+      }
+    );
+  });
+
   it('uncolorize() not crashing with Symbol()', assumeFormatted(
     combine(
       format(info => {
@@ -115,6 +143,23 @@ describe('uncolorize', () => {
     }
   ));
 
+  it(
+    'same uncolorize({ level: false }) removes color from { message, [MESSAGE] } when NO_COLOR env var is enabled', () => {
+      process.env.NO_COLOR = 'true';
+      assumeFormatted(
+        addAndRemoveColors({ level: false }, true),
+        infoify({ level: 'info', message: 'whatever' }),
+        info => {
+          assume(info.level).is.a('string');
+          assume(info.message).is.a('string');
+
+          assume(info.level).equals('info');
+          assume(info.message).equals('whatever');
+          assume(info[MESSAGE]).equals('info: whatever');
+        }
+      );
+    });
+
   it('uncolorize({ message: false }) removes color from { level, [MESSAGE] }', assumeFormatted(
     addAndRemoveColors({ message: false }),
     infoify({ level: 'info', message: 'whatever' }),
@@ -147,7 +192,6 @@ describe('uncolorize', () => {
     info => {
       assume(info.level).is.a('string');
       assume(info.message).is.a('string');
-
       assume(info.level).equals(colors.green('info'));
       assume(info.message).equals(colors.green('whatever'));
       assume(info[MESSAGE]).equals('info: whatever');