This review summarizes published studies on undergraduate mentoring programs from 2008 to 2012. Twenty studies met the inclusion criteria, which included empirical research on formal mentoring programs with undergraduate students as mentees or mentors. Each study was assessed based on limitations identified in two earlier reviews of the mentoring literature: definition, theory, and methods. Results from this review indicate minimal progress has been made in these three areas. However, every study included the functions of mentoring, and most studies were guided by a theory or a conceptual framework. Aspects of social validity, a construct not previously examined, were assessed and found to be present in 50% of studies. Finally, information on primary mentoring program components, another dimension not previously examined, was absent in 75% of studies, making replication difficult. Future research needs to specify program components, employ rigorous research designs to guide evidence-based practice in undergraduate mentoring, and assess social validity.