Purpose/Hypothesis: The purpose of this study is two fold: to investigate, in unperturbed walking, whether step width or frontal plane center of mass (COM) control can predict a person's ability to recover from an induced slip; and to investigate the extent to which frontal plane COM and BOS control during an anterior posterior (A-P) slip affect the outcome of the slip. We hypothesize that the step width and frontal plane COM control exhibited during natural gait and during the first, unexpected slip, will differentiate between those who will be able to recover from an induced slip and those who will not. Subjects: 34 healthy adults, 65 years and older. Materials/Methods: Subjects walked on an instrumented walkway while wearing a safety harness during motion capture of their regular gait. After 10 unperturbed trials, an AP slip was induced unexpectedly under the right heel at touchdown (TD). Motion data were used to calculate the frontal plane variables step width, COM position, normalized COM position, and COM velocity. These were calculated at right heel TD, left foot lift off (LO), and subsequent right foot touchdown (RCTD). Subjects were grouped by outcome of the first slip trial into the fall or the recover group. T-tests were used to compare the frontal plane variables at the three gait instants for the fall vs. the recover group for natural walking and for the slip trial. Results: Upon the first slip, all 34 subjects experienced a loss of balance: 19 subjects fell (fall group), the other 15 did not (recover group). During unperturbed walking, at TD and LO, there were no differences in the frontal plane variables between the fall group and the recover group. At left touchdown (RCTD), there were small, but significant differences in the lateral position of the COM and the step width between the two groups; but no differences in normalized COM position or COM velocity. At the three gait instants examined during the first, unexpected slip, there were no differences between the fall group and the recover group in step width, or any of the other frontal plane COM variables measured. Conclusions: Altered frontal plane center of mass control in stance, stepping, normal walking, and perturbed gait, as well as increased step width during gait, have been implicated as risk factors for falling associated with aging. We, therefore, expected step width and frontal plane COM control during natural walking and throughout a slip to be different between the group who fell as a result of the slip and those who were able to recover. We found only small differences during natural walking and none during the slip. Clinical Relevance: Balance and gait training in older adults which have the goal of fall prevention should focus on those areas which pre-dispose one to falling. In this case, step width and lateral control of the body's COM, during natural gait and during a slip, appear not to have been, as is frequently believed, related to the subject's ability to recover from an induced slip.