Introduction: Schools meals offer a critical opportunity for improving youths' diets, particularly for economically disadvantaged students. We examine the impact of a multipronged intervention to increase middle and high school students' lunch participation in an urban school district. Methods: In school years 2015-2016 through 2017-2018, a quasi-experimental study was conducted in 24 secondary schools, half (n = 12) of which received the following intervention: cafeteria redesign, additional school lunch points-of-sale (mobile carts and vending machines), and teacher education. Results: From baseline to follow-up, lunch participation dropped 4.1% in intervention and 5.1% in comparison schools (difference-in-difference 1.0%, 95% CI 0.5-1.4). The overall decline in lunch participation occurred simultaneously with a drop-in free or reduced-price meal eligibility (from 72% to 58%) across all schools, which is likely related to changing local economic conditions, including a county-wide minimum wage increase that began in summer 2015. Among students eligible for free or reduced-price meals, participation decreased 1.8% in intervention and 4.9% in comparison schools (difference-in-difference 3.1%, 95% CI: 2.5-3.7), with a larger difference-in-difference seen in high schools (5.0%, 95% CI: 4.2-5.9) than middle schools (1.8%, 95% CI: 0.8-2.6). Conclusions: While this intervention demonstrated a modest, but significant relative increase in school lunch participation, the effect was not sufficient to halt large district-wide declines in participation during this study period. Given the significant time, money, and political capital required to implement the intervention, districts should carefully consider similar investments. Broader public policies or other changes to economic conditions that affect eligibility for means-tested benefits-in this case, a strengthening local economy coupled with an increased local minimum wage-may influence school lunch participation more than school-level interventions.