In order to align with university-wide assessment initiatives and to promote a systematic approach to one-shot assessment within our library, a team of five librarians participated in a campus-wide professional development program about student learning assessment. We then implemented library-specific professional development about student learning assessment for one-shot instruction. We provide an overview of the professional development program and discuss our study that explored the impact of the program on librarians' knowledge, skills, and attitudes about student learning assessment. Our findings indicate that faculty participants had a positive change in practice, knowledge, and attitude after participating in the professional development program.