Abstract: Practically all workers move from one firm to another at some point in their careers, and a growing body of research has shown that in the past four decades such mobility in the labor market has become more frequent. What is less well known is how potential employers today perceive job applicants who have been more or less mobile. Job instability acts as one of several signals on a resume. In this paper, we ask how employers judge and interpret these signals to predict worker quality. We investigate the potential impact of two competing career models that attribute a different signal to job mobility, and more specifically to job hopping among US workers seeking a senior-level position. The traditional career model is perhaps best exemplified by the “mailroom to boardroom” success story, which conveyed the message that commitment to a single employer is a key strategies for success. The dominance of the traditional career model came under fire with the rise of flexible employment practice, and a new career model has emerged that academics refer to as the boundaryless career. In contrast with the traditional career model that emphasizes loyalty, this model proposes that careers spanning multiple employers will be not only more successful but also more personally rewarding. The main objective of our study, therefore, is to measure the responses of employers to different types of mobility histories of job applicants and the possible causes of variation in employer responses. We also assess whether employer reactions to work histories vary systematically by occupation, gender and industry. Our results are based on a resume audit study where the key experimental manipulation is the level of mobility in the job history of our fictious applicants. In preliminary data, we find a lower call-back rate among job hoppers compared to workers exhibiting a moderate or low level of mobility, except among tech workers. These results support the idea that a boundaryless career model may diminish the hiring prospects of non-tech workers.