We describe challenges to measuring the type and quantity of mental health programs, practices, and resources that schools provide to students, as well as variation in these resources. We conducted interviews and surveys with school and district staff representing 55 middle and high schools in MetroWest Massachusetts with the goal of collecting data on (1) school-wide preventive services, (2) use of mental health screenings and anonymous reporting systems, (3) supports for specific student populations, (4) mental health supports and services, (5) community partnerships, and (6) staff trainings in mental health. Findings revealed wide variation in the programs, services, and resources that school staff described providing to students, as well as specific challenges in systematically collecting these data. We discuss the implications of these challenges, including barriers to documenting which resources are used by schools and studying which are most effective in connecting youth with needed mental health services. We conclude with implications for school psychologists and suggestions for researchers and policymakers seeking to better understand and document school provision of mental health resources.