I use a large sample of jobs from the National Longitudinal Survey of Youth to examine job mobility patterns and to evaluate theories of interfirm worker mobility. There are three main findings. First, the monthly hazard of job ending is not monotonically decreasing in tenure as most earlier work using annual data has found, but it increases to a maximum at 3 months and declines thereafter. Second, mobility is strongly positively related to the frequency of job change prior to the start of the job. Finally, job change in the most recent year prior to the start of the job is more strongly related than earlier job change to mobility on the current job.
