This document provides guidance on conducting a rapid cumulative impact assessment (RCIA) for private sector projects in emerging markets. It outlines a six-step RCIA process involving scoping, determining environmental and social baselines, assessing cumulative impacts and their significance, and designing mitigation measures. The RCIA is intended as a preliminary screening that may evolve into a more comprehensive CIA. It recognizes that effectively managing cumulative impacts often requires coordination between multiple stakeholders, which can be challenging in emerging markets where data and governance capacity are limited.