The professional development (PD) opportunities typically offered to school music teachers in most countries have been described as sporadic, unsystematic, capricious in both purpose and content, and hence ineffective. Among other consequences, this has seriously limited the kinds of questions that music-specific PD researchers have been able to investigate. The situation is considerably different in Singapore, where in the past years music teachers have been offered a plethora of music-specific PD initiatives with various features (e.g., content, working dynamics, duration). Using Desimone's (2009) framework of critical features for effective PD, developed with teachers of "core" subjects, in this study we investigate the features of the most and least helpful PD as reported by Singapore primary music teachers. We conducted two focus group discussions (n = 7, n = 5) and a nationwide survey (n = 98). Data were analyzed using content analysis and descriptive/parametric statistics, respectively. Results showed that the participants prefer long and work-intensive PD initiatives focused on a mix of content directly applicable in class. They also value having active learning opportunities and interacting with familiar fellow colleagues. Teachers' responses suggest that all these high-quality features have to be met for a PD initiative to be deemed helpful. We conclude that Singapore music teachers also value the features described in Desimone's framework. Policy makers and school administrators should be mindful not only of the need to provide music teachers with more PD opportunities, but also of the need to offer PD that meets certain quality standards. This study has the potential to guide PD providers in how to best invest the resources available to better foster music teachers' professional learning.