This topic guide aims to support practitioners (local authorities, mobility experts, consultants, and international development officials) in deciding the best solution to implement transport modelling when preparing a Sustainable Urban Mobility Plan (SUMP). Desk review and the experience of some MobiliseYourCity city members constitute the basis of the content presented. This topic guide provides insights into transport modelling and its pertinence and suggests a step-by-step guide to integrate this analysis tool when preparing a SUMP. Accordingly, the ambition of this document is not to provide ready-to-use solutions that others could replicate in every context. This topic guide aims to propose a methodology of reflection and a set of questions to ask oneself to build a coherent, realistic, and locally-based transport model, if needed.