The inadequacy of training and support for academic middle managers in the US, UK, and Australia is well documented. What remains unclear is what would make for better professional development. This study fills this gap by investigating what associate deans at US research universities report learning 'on the job'. Drawing on their perspectives and experiences, as documented via semi-structured interviews, this study found that associate deans spend significant time and effort learning how to make administrative decisions, learning how the university works for the purposes of making decisions, learning how to manage people relative to decision-making processes and outcomes, and learning how to manage themselves with regard to their decision-making role. It is argued that professional development for associate deans should focus on administrative decision-making as an essential skill in learning to lead. Recommendations for a curricular framework that can be adapted to individual-, role- and context-specific needs are offered.