This paper analyzes labor force re-entry after retirement in an effort to understand whether these “unretirement” transitions are largely unexpected (perhaps resulting from failures in planning or unexpected financial shocks) or planned (perhaps representing a more complex retirement process). Nearly one-half of retirees follow a nontraditional retirement path that involves partial retirement and/or unretirement, and the unretirement rate among those observed at least five years after their first retirement is 24 percent. The unretirement rate is even higher among those retiring at younger ages (as high as 36 percent among those retiring at ages 51-52). I find that unretirement was anticipated for all but nine percent of retirees. If anything, expectations err on the side of excessive pessimism about the future rather than unwarranted optimism. Unretirement appears to be qualitatively similar to partial retirement and there is some evidence of a substantial correlation in the post-retirement labor supply transitions of married couples.