Determining a neurophysiology code for color from single cell studies meets with some difficulty, because most visual neurons in primates change their activity as a result of a change in stimulus intensity, spectral composition, form or position. It is argued in the present paper that the activity of a single neuron cannot be considered as the neural representation of a stimulus, but instead, stimulus encoding must be viewed in terms of the relative amounts of neural activity produced in many parallel neurons at various stages of the visual pathway. This “across-neuron pattern” code for color is used to account for color sensations and bue discriminations in normal trichromats and dicbromats. The neural basis of brightness and saturation are all discussed.