A set of psychophysical experiments was conducted to investigate backgrounds for determining the adapted white points of CRTs viewed under variously illuminated environments. A number of background characteristics were modified, such as pixel size, chroma range and lightness range. All backgrounds tested averaged to the same luminance and chromaticity. Observers viewed solid-colored samples on a field of each background displayed on a D65 balanced CRT monitor in a dark environment. Their task was to select the most achromatic appearing samples through an iterative process. Only two of the six backgrounds were found to result in near complete adaptation to the monitor: the control, a solid field of L*=60, and, an achromatic random dot pattern. None of the other tested backgrounds, which were all chromatic random dot patterns, resulted in complete adaptation, and all had very large variances. The conclusion is drawn that chromatic random backgrounds can significantly effect chromatic adaptation. This is true even if the measured background is neutral and if the background pixels average to an achromatic.