The present investigation aims to test the validity of scores on the math homework purpose scale (MHPS) for high school students. Factorial results found that the MHPS contained three subscales: academic purpose, self-regulatory purpose, and approval-seeking purpose. Furthermore, the MHPS had a sufficient level of measurement and latent factor mean invariance across gender and grade level. Additionally, the MHPS had adequate coefficient alpha and omega coefficients. Regarding its validity evidence, consistent with theoretical predictions, the MHPS was associated positively with homework effort and completion. In summary, our investigation presents strong evidence showing that the MHPS is a valid tool for use with high school students.