Drawing from data on over 1000 prospective teachers in a large urban district including pre and post-student teaching survey data, this study investigates whether lengthening student teaching improves teachers' perceptions of instructional preparedness, efficacy, and career plans. The findings suggest that the duration of student teaching has little effect on teacher outcomes; however, the quality of student teaching has significant and positive effects. Moreover, the magnitude of the effects of student teaching quality are greater when student teaching is shorter and in schools with more historically underserved racial groups. The authors discuss policy implications and directions for further research. (Contains 11 tables and 3 figures.)