The case study investigation reported here assessed California 4-H professionals' understanding of the essential components of effective 4-H Science programming as established by the National 4-H Science Mission Mandate. Using the 4-H Science Checklist as the basis for defining 4-H Science Readiness, academic and program staff were surveyed and interviewed to determine their understanding of what constitutes effective science programming in 4-H and their capacity to deliver science professional development and programs. Results indicated a need to build staff capacity relative to 4-H Science in California and outcomes may have implications for 4-H professionals nationally.