Evaluation has become a common, and even an expected, practice across undergraduate mathematics tutoring centres in the USA, UK and other countries. However, these evaluation efforts could benefit greatly from leveraging organizational theory research. In this study, we situate mathematics tutoring centres as non-profit organizations (NPOs) to consider how an organization performance assessment framework can be adapted to study mathematics tutoring centre data and characteristics. We use qualitative and quantitative data, collected from six mathematics tutoring centres and adapt Lee & Nowell's (2015, "Am. J. Eval.," 36, 299-319) NPO performance framework to situate our study. Using thematic analysis, the research team underwent iterative cycles of data collection and analysis to code for alignment with Lee and Nowell's framework. By adapting Lee and Nowell's framework to mathematics centres, each of the six centres was given a more relevant lens to consider its performance. Regardless of the university setting, previous evaluations for centres have focused primarily on outputs (e.g., number of visits), behavioural change outcomes (e.g., correlating visits to grades) and client satisfaction outcomes (e.g., student surveys) that ignore the particular context of a centre. However, Lee and Nowell's framework takes into account additional performance indicators that provide a more nuanced understanding of a centre's performance by bringing to light the interplay among its various dimensions. Lee and Nowell's framework allows centres to look beyond outputs and outcomes to understand why these outputs and outcomes come to be. The use of this adapted performance framework, for the six mathematics centres in this study, allows an interpretation on a variety of dimensions using relevant data while indicating possible areas for change for each centre.