Although aging is normally associated with declines in motor performance, recent evidence suggests that older adults suffer no loss in some measures of bimanual coordination relative to younger adults. Two hypotheses for this finding were compared in the present research. One hypothesis was based on the assumption that these coordination patterns are automatic and relatively impervious to the effects of aging. An alternative explanation is that older adults maintain this level of bimanual coordination at a cost of increased attention demand. These hypotheses were tested in an experiment in which bimanual coordination patterns (in-phase and anti-phase) were paced at two metronome frequencies (1 and 2 Hz), either alone or together, with serial performance of an attention-demanding task (adding 3s to a two-digit number at a 1 Hz pace). The results of the study provided some support for both hypotheses. The automaticity view was supported only for the coordination patterns at the 1 Hz metronome frequency. Support for an attention allocation hypothesis was shown in the observed-movement frequency data, as older adults tended to sacrifice movement frequency at the 2 Hz metronome pace in order to maintain performance in the movement and counting tasks. These findings are discussed relative to recent accounts of the role of automaticity in the absence of age-related differences in the performance of cognitive tasks.