Humanitarian actors in emergencies often encounter challenges in knowing Who is Where, When, doing What (4Ws) with regard to mental health and psychosocial support (MHPSS). Such knowledge is essential to inform coordination. 4Ws tools are used in many areas of aid to map activities conducted across large geographical areas". This manual outlines the 4Ws with regard to mental health and psychosocial support for humanitarian actors with MHPSS coordinating responsibilities. The tool exists in two parts: a 4Ws data collection spreadsheets application (in excel online) and this manual which describes how to collect the data