This paper focuses on both traditional and current competencies-defined as the knowledge, and skills and abilities to carry out one's responsibilities in building relevant collection for given user populations in a specific institutional and scholarly environment, some of the competencies are broad and theoretical, while others are specific and highly technical. Both approaches are needed especially in an era of rapid change. Itself, is another key competency-mastering this will help the science collections librarian, and the collections they build remain relevant well into, the future.