First published in 1979. This thesis describes the theoretical impact on labour markets of a process of adverse selection similar to that described in outline by George Arthur Akerlof. It concerns the information conveyed to potential employers by the fact that any new worker, except for one just entering the labour force, has either left or is prepared to leave his latest Job. If an employer is able to identify his good workers more accurately than the market at large and is generally successful in retaining them, then the group of workers leaving him will contain a disproportionately...