Phased retirement may be defined as a transition path whereby an older employee shifts from full-time to part-time work without changing employers. An interesting aspect of phased retirement is that it sometimes occurs after the older employee officially “retires”. Then the recently retired employee is rehired, and the two events are sometimes separated by less than a week. This chapter makes use of a national survey of 950 establishments to address the question of why an employer might make use of such an arrangement. We find that most employers might be willing to informally-arranged reductions in hours both before and after official retirement, and few impose a formal “waiting-time” between official retirement and subsequent rehire. We test several hypotheses about why employers might prefer that phased retirement occur before and/or after official retirement. Our results suggest that pensions, existing employment arrangements, and organizational size play a role. It is likely that such individually-negotiated arrangements will become an ever-more important element of the evolving retirement paradigm.