This article investigates the effects of services proposed by private developers on buyers’ psychological attitudes in the decision-making process for off-plan purchases. We propose a new typology of services based on perceived value. We conducted a field experiment with real buyers who purchased an off-plan dwelling in France, and we measured the causal effects on developer reputation of four service intensity indexes that offer ‘visualisation’, ‘customisation’, ‘value enhancement’ and ‘interaction’ services. The results confirm the homebuyer-based typology of services and highlight the mediating roles of two types of attitudes, satisfaction with and trust in the developer, to explain the influence on developer reputation. Services designed to improve the perception of the quality of the dwelling itself (visualisation and customisation benefits) are less effective, and those intended to create a favourable purchase context (value enhancement and interactional benefits) are more influential, emphasising the benevolent role expected from developers.