Positional behavior in adult red colobus monkeys (Colobus badius) was examined in a variety of ecological contexts. Using a focal-animal methodology, we assessed how data collected by different observers, in different years, in different seasons, and in different forests affected estimates of positional behavior. In all, 23,000 bouts were recorded. Variation in frequency is greatest in the common behaviors, especially arboreal quadrupedalism. Significant behavioral differences occur more often in the context of different forests than in annual or seasonal comparisons. The activity of feeding exhibits the largest frequency changes across positional behavior and ecological context. In all, red colobus monkeys exhibit substantial amounts of flexibility in positional behavior across different ecological contexts. © 1995 Wiley-Liss, Inc.