Four groups of six male social drinkers learned a motor skill task and then drank the same dose of ethanol (0.62 g/kg) during each of five drinking sessions. Sessions 1 and 5 provided pre- and posttreatment measures of ethanol effects on task performance. During treatment sessions 2 to 4, two groups mentally rehearsed (MR) the task after drinking, either in the same test environment (MRSE) or in an entirely different environment resembling a library (MRDE). The other two groups received no MR after consuming ethanol, and simply performed an auditory detection task, either in the same test room (NMRSE) or in the different room (NMRDE). Posttreatment impairment of task performance under ethanol revealed significant main effects of mental rehearsal (P = 0.04) and environment (P = 0.04). The MRSE group was least impaired (i.e., most tolerant), and the NMRDE group was most impaired. Thus, repeated mental rehearsal and repeated exposure to the same test environment under ethanol each facilitated behavioral tolerance to ethanol.