Stability improvements made in a single acquisition session with merely 5 slips in walking are sufficient to prevent backward balance loss (BLOB) at the end of session, but not after 12 months. The purpose of this study was to determine whether the effect of an enhanced single acquisition session would be retainable if tested sooner, at intervals of up to 4 months. Twenty-four young subjects were exposed to blocks of slip, non-slip, and both types of trials during walking at preferred speeds in the acquisition session. In each of the 4 follow-up sessions around 1 week, 2 weeks, 1 month and 4 months later, these same subjects experienced only a single slip following 8-13 unperturbed walking trials in an otherwise identical setup. Gait stability was obtained as the shortest distance between the measured center of mass (COM) state (position and velocity) and the mathematically predicted threshold for BLOB at pre- and post-slip, corresponding to the instants of touchdown of the slipping limb and liftoff of the contralateral limb, respectively. During the acquisition session, pre- and post-slip stability improved significantly, resulting in a reduction of BLOB from 100% in the first slip (S1) to 0% in the last slip (S24), with improvements converging to a steady-state, that enabled all of the subjects to avoid BLOB, regardless of whether a slip occurred or not. During retest sessions, subjects' pre-slip stability was not different from that in S24, but greater than that in S1. Their post-slip stability was also greater than in S1 but less than in S24, resulting in BLOB at a 40% level. No difference was found in any of these aspects between each follow-up session. These adaptive changes were associated with a range of individual differences, varying from no detectable deterioration in all aspects (n = 8) to a consistent BLOB in all follow-ups (n = 3). Our findings have demonstrated the extent of plasticity of the central nervous system, characterized by rapid acquisition of a stable COM state under unpredictable slip conditions and retention of such improvements for months, resulting in a reduced occurrence of unintended backward falling.