Background/Context: In response to a shortage of highly qualified teachers, states and school districts have enacted a number of policy innovations over the last two decades. While researchers have evaluated many of these reforms, little is known about the initial effectiveness of individuals with prior teaching assistant experience. We review existing literature related to teaching assistants and utilize administrative data to examine a number of characteristics of individuals who transition from work as teaching assistants to jobs as regular classroom teachers. Study Purpose: Individuals who become classroom teachers after having prior experience in schools working as teaching assistants may perform differently than other teachers due to additional exposure to classroom practices. The purpose of this study is to identify differences in the characteristics, effectiveness, and persistence of teachers who work as teaching assistants prior to entering the classroom as regular classroom teachers. Population: While the population of focus varies somewhat across research questions, we generally focus on teachers with less than five years of experience working in elementary and middle school grades in all North Carolina public schools from 2005-2006 to 2009-2010. Additional data on teaching assistants employed from 2000-2001 to 2009-2010 in North Carolina public schools allows identification of individuals who had prior experience as teaching assistants in the state. Research Design: Using administrative data records, we utilize quantitative descriptions of teacher characteristics and persistence to identify differences between teachers who entered the classroom with prior teaching assistant experience and other groups of teachers. For effectiveness comparisons, we estimate value-added models to compare the effectiveness of teachers in the identified groups of interest. Findings/Results: Overall, we find that teachers who began as teaching assistants are (1) older, more racially diverse, lower-scoring on licensure exams, and more likely to enter the profession alternatively; (2) more effective in elementary-grades math and reading; and (3) more likely to remain as classroom teachers in North Carolina public schools. Conclusions/Recommendations: These findings indicate that former teaching assistants represent a quality and highly persistent labor source and call for continued research to understand how additional exposure to classrooms benefits early-career teacher performance.