This is the full technical evaluation report on the Louis Stokes Alliances for Minority Participation (LSAMP) program--a National Science Foundation effort to increase the pool of underrepresented minority students receiving bachelor's degrees and pursuing graduate studies in science, technology, engineering and mathematics (STEM). Utilizing quantitative and qualitative methods, the evaluation describes LSAMP's implementation and assesses whether it achieved its goals. Findings reveal that LSAMP graduates are more likely to enroll in and complete graduate programs in STEM than nationally-representative comparison groups. Program staff report that LSAMP expanded institutions' ability to develop STEM talent. A research-based descriptive model of the program is included, reinforcing the link between theory and practice in effective interventions.