Although music is the fundamental element of music therapy, music analysis methods are a particularly under-researched area. This study investigates how and when psychodynamically orientated music therapists employ the analysis of musical material in both clinical work and research. Constructivist grounded theory was employed in the collection and analysis of the data. Eight participants, all highly experienced in psychodynamic music therapy, were recruited using referral sampling. In-depth interviews focused on therapists’ experiences of working with different client groups, and the applicability of different assessment methods. Strauss and Corbin’s coding paradigm was used to determine causal and intervening conditions, action strategies and the consequences of music analysis. Professional freedom (a tension between creative forces and professional responsibilities) emerged as the most important factor influencing the method, application and frequency of music analysis. Therapists used either explicit knowledge (model-based theoretical understanding and reductionist action strategy), or implicit knowledge (context-based theoretical understanding and holistic action strategy) or used a combination of both approaches. Implicit knowledge was found to lessen the ability to give an account of analytical processes, but increased sensitivity to clients’ abilities and needs, while explicit knowledge led to frustration about interdisciplinary disagreement, greater excitement about discovery and increased workloads.