This study is a literature review of research related to the characteristics of second careers undertaken after mid-life. There is a significant lack of literature directly on this topic, so we draw substantially from the literatures about retirement, bridge jobs, encore jobs, and unretirement. First, we provide a working definition of second careers after mid-life. We then provide a brief background of the existing theoretical research related to this topic, which is also in need of updating and synthesis. We find evidence that second careers may already be common, but likely are undertaken by less than half of older workers. For older workers in general, job flexibility and lower stress seem to be particularly prized job characteristics that they seem willing to trade off against earnings, benefits, and prestige. However, individual fit is also likely to be particularly important in learning about second careers. We also find useful information in studies of specific early-retiring occupations and destination second careers. Based on the existing general, late-life labor supply literature and specific occupation literature, we propose new directions for research. An important take-away is that data limitations have been a roadblock; however, forthcoming resources may help open up this area of research.