This paper presents a study of the specific disciplinary competencies required of library programming professionals and the training pathways where they develop those skills. Most existing competency frameworks focus on general library service or audience, rather than the specializations required for public programming. Reflecting the emerging importance of programming to libraries' service model, this US research study demonstrates that excellence in programming requires a unique set of competencies not found in other areas of library practice. The evidence shows that most public-programming competencies are learned outside of MLIS training but could be introduced as an MLIS concentration or learned as professional development.