The research aimed to estimate educational psychologist (EP) service provision required to deliver a "good" level of EP service within primary and secondary schools in one local authority (LA) in England. There is no current shared understanding of the level of demand for EP services, nor the required workforce to meet projected needs. Using a mixed methods design, four index schools were recruited; key staff within each school forecasted potential future commissioning of EP services. Content analysis was used to present key findings from focus groups/interviews to a working group of EPs who assessed the exact time-cost required to supply services. By extrapolation of the data, a model forecasted potential future demand for EP services across all primary and secondary schools in the LA. Findings reveal that all four schools would, with sufficient funding, commission significantly more EP time than they do currently; details and proportions are provided. The model predicts that schools across the LA would commission a fourfold increase in EP time purchased. Under the assumption that other EP service levels remain constant, the model suggests that meeting this need for increased EP services would require more than doubling of the size of the LA EP workforce.