Contribution: This study demonstrates the efficacy of an ecological belonging intervention in a first-year engineering programming course to increase belonging for Black, Latinx, and Indigenous (BLI) students and close academic equity gaps. Background: Introductory programming courses are often challenging for students and can shape belonging in engineering. BLI students may be particularly susceptible to interpreting struggle as confirmation that they do not belong in predominantly white spaces, which can negatively influence academic outcomes. Research Questions: "What are the effects of an ecological belonging intervention on BLI students' feelings of belonging within their first-year engineering course?" and "What are the effects of an ecological belonging intervention on BLI students' performance on a weekly computer programming assignment?" Methodology: The intervention was implemented with 691 students in Spring 2022 and was designed to normalize the struggle to address threats to belonging and close equity gaps in BLI students' academic performance. A pre-/post-semester survey measuring belonging was analyzed using repeated-measures ANOVA, and pass/fail academic records were analyzed using logistic regression. Findings: The targeted belonging intervention for BLI engineering students can help to address issues of isolation and academic confidence that negatively impact individuals' sense of belonging and academic performance.