The purpose of this study was to examine the effects of a school-wide attendance and truancy intervention and universal procedures (ATI-UP) on student attendance. Student attendance was measured through average daily attendance and the percentage of students who would be considered chronically absent, i.e., missing 10% or more of school. The sample included 27 elementary schools in Oregon implementing school-wide positive behavior intervention and supports (SWPBIS) with varying levels of fidelity. Results indicate that schools can have a moderate effect on increasing average daily attendance (ADA) and a small effect on decreasing chronic absenteeism, although these results were not statistically significant. SWPBIS implementation did not act as a statistically significant moderator on the ATI-UP effects, although the treatment effect on ADA decreased with higher SWPBIS implementation.