INTRODUCTION & AIMS In team sports, training is strategically designed to incorporate all training factors (i.e., physical, technical, tactical, mental) to improve an athlete’s performance during competition. The ultimate goal is for individual athletes to work together as a cohesive unit to complete training objectives and train at high quality. Although anecdotal, training quality is considered a key component in the training process. However, there is currently no team sport literature that has defined this construct. Nor a validated measurement instrument available to assess the quality of team sport training. Therefore, the present study developed the Subjective Training Quality for Team Sports (STQ-TS) scale. Furthermore, this study investigated the application of this scale within the context of a professional National Rugby League (NRL) team. METHODS Eleven rugby league players (24 ± 2 y; 62 ± 47 NRL games) were interviewed to explore how they define and assess training quality. Thematic analysis was used to analyse interview transcripts. The identified themes were used to develop a preliminary STQ-TS scale. The STQ-TS scale was completed by forty-two NRL players across two seasons. RESULTS Four themes were identified for the STQ-TS scale. These themes included physical, technical, mental, and teamwork (i.e., communication; connectedness). Players perceived pre-season training to be lower quality compared to in-season. In-season training quality showed a gradual improvement throughout both seasons, reaching its peak late in the season. CONCLUSION Professional rugby league players perceive training quality as their ability to complete physical, technical, mental, and teamwork objectives. The STQ-TS scale serves as a valuable tool for practitioners to assess training quality in team sports. The integration of the STQ-TS scale with external load, internal load, and athlete response measures can provide practitioners with a more nuanced and holistic understanding of the training process.