Workers can build their careers either by moving into a different job within their current organization or else by moving into a new job within a different organization. We use matching perspectives on job mobility to develop predictions about the different roles that those internal and external moves will play within their careers. We propose that internal and external mobility are associated with very different rewards: upwards progression into a job with greater responsibilities is much more likely to happen through internal mobility, but external moves will nonetheless offer similar increases in pay, as employers seek to attract external hires. We also examine how these predictions change when moves take workers across job functions as well as when external mobility happens involuntarily. Analyses of data on the careers on MBA alumni are used to support these arguments. Despite growing interest in boundaryless careers, our findings indicate that internal and external mobility play very different roles in executives’ careers, with upwards mobility still happening overwhelmingly within organizations.