Although the development of professional identity is thought to play a central role in the career development process, little empirical research has examined change in professional identity over time and its connection to adjustment and persistence in a professional field of study. In this research, latent growth modeling was used to examine the effects of pre-college professional identity and change in professional identity through the first year of college in a sample of engineering students (N = 295). Results indicated that professional identity prior to entering college and rate of change in professional identity over the first year of study were related to major embeddedness dimensions of fit (i.e., match between oneself and the major), links (i.e., professional connections), and sacrifice (i.e., costs and benefits associated with leaving the major). Rate of change in professional identity was also positively related to persistence in the engineering major the following year. Despite the general utility of professional identity in predicting embeddedness, men and women differed in several important parameter estimates. This research suggests professional identity development is best conceptualized and empirically examined as a dynamic process that occurs over time, contributes to understanding of the factors underlying adjustment and persistence of women and men in STEM career pathways, and emphasizes the importance of fostering pre-college professional identity and professional identity development early in professional programs of study.