This field guide introduces human-centred design as an approach to addressing challenges related to community demand for services (specifically immunization services, but it could be applied to others). This Field Guide exists to help investigate, understand and respond to challenges of demand. It draws on insights from behavioural science and employs human-centred methods to improve immunization outcomes. Includes a 170 page field manual, process map, and workbook with tools. Its process overview poster provides guidance on who to involve and expected time investment for each method in the process.