This document is about providing guidance on conducting cross-regional and auxiliary investigations of employee benefit plans and service providers. It encourages collaboration between regional offices to achieve more efficient use of resources, consistent enforcement policies, and a better understanding of national issues. The document outlines the characteristics of cases appropriate for cross-regional investigations, such as large plans, multi-client service providers, complex issues, and resource-intensive or time-sensitive cases. It also describes ways for regional offices to collaborate, including introducing investigations, opening a joint investigation, leading an investigation, and providing investigative expertise. For limited investigative needs outside the primary office's jurisdiction, the document outlines the process for requesting auxiliary investigations from the appropriate regional office.