In order to enhance the quality of education, school self-evaluation (SSE) has become a key strategy in many educational systems. During an SSE process, schools describe and evaluate their own functioning, often by administering questionnaires among teachers. However, it is unknown to what extent SSE questionnaire results are distorted by respondents' tendencies towards socially desirable responding and their motivation to fill in an SSE questionnaire. This study reports on a path analysis, performed on the results of an authentic SSE with 382 participants. Results indicate that socially desirable responding and motivation have indeed an impact on SSE results. However, the effects are differential and depend on the variable of interest. These findings can have serious implications, and should be taken into account when drawing conclusions and taking (school) policy decisions within the framework of an SSE process.