Self-monitoring interventions are well supported within the empirical literature as improving classroom engagement for students with disabilities. However, studies implementing self-monitoring interventions in high school settings are rarely conducted despite their potential to improve student academic and behavioral outcomes. In an investigation of an unobtrusive, self-monitoring application loaded on a handheld device, classroom engagement and perceived academic benefits were assessed in a withdrawal design for three high school students with different disabilities (specific learning disability, autism, and intellectual disability) in varied instructional arrangements. Direct observation data supported the intervention as effective in improving classroom engagement for all three students during intervention and maintenance phases.