Collective impact (CI) is a structured approach that helps drive multi-sector collaborations to address social problems through systems changes. While the CI approach is gaining popularity, practitioners experience challenges in evaluating its implementation and intended outcomes. We conducted a systematic scoping review to understand evaluation methods specific to CI initiatives, identify challenges or limitations with these evaluations, and provide recommendations for the design of CI evaluations. Eighteen studies met the inclusion criteria. Process evaluations were the most frequently used evaluation design. Most studies collected cross-sectional data to evaluate their efforts. The complexity of CI was most frequently cited as the greatest evaluation challenge. Study recommendations primarily focused on improvements during the evaluation planning phase. Taking careful consideration in the planning of CI evaluations, developing context-specific data collection methods, and communicating results intentionally and effectively could prove useful to sufficiently capture and assess this systems-level approach to address social problems.