Dr. Hal Abeles is a foundational leader in developing music performance assessments, conducting program evaluations of arts partnerships, and publishing basic research on the effects of arts instruction on learning in and across cognitive, social and personal domains. This article explores the theoretical and practical issues in music performance assessment and program evaluation, and how Dr. Abeles clarified, explicated, and created solutions with a broad and deep influence on music and arts education. Dr. Abeles modeled the application of the facet-factorial method for developing assessments of musical performances. Originally designed for assessment of clarinet performance, the method was adapted and re-applied to develop metrics for many other musical instruments, ensembles, and for jazz improvisation. Further extension of the facet-factorial method were used develop tools for assessing teacher professional development and evaluating arts partnerships. In addition, Dr. Abeles conducted seminal research on the effects of arts learning on thinking skills, affective learning, self-confidence and school engagement, published by the President's Committee on the Arts and Humanities. The study, Learning In and Through the Arts, found significant relationships between participation in the arts and dimensions of cognitive, social and personal development, that were inherent to arts learning and also applicable to student development in other domains and contexts. Additional applied research examined the impact of partnership programs on teachers' pedagogy, leadership, musicianship, and students' interest in pursuing music.