Rainfall-derived infiltration and inflow (RDII) into sanitary sewer systems has long been recognized as a major source of operating problems, causing poor performance of many sewer systems. RDII is the main cause of SSOs to customer basements, streets, or nearby streams and can also cause serious operating problems at wastewater treatment facilities. There is a need to develop proven methodologies and computer tools to assist communities in developing SSO control plans. To accomplish this goal, USEPA entered into a cooperative research and development agreement (CRADA) with Camp Dresser & McKee, Inc. to develop public-domain software tools. These tools, named the Sanitary Sewer Overflow Analysis and Planning (SSOAP) Toolbox, are accompanied by this technical document that describes how to use the Toolbox for the analysis and development of SSO control plans. This report identifies a RDII prediction methodology for the Toolbox, and provides an overview of the required sewer system hydraulic analysis and data collection requirements. In addition, the report describes the use of SWMM5 for performing system capacity assessment. Guidance is provided for establishing objectives, and developing and screening improvement scenarios. Finally, a case study was included to demonstrate the use of the RDII methodology described in this technical report in SSO analysis and planning.