This study aims to understand the influence of the quality of service in the consulting relationship and the interaction between the service provider and the client. Specifically, we aim to understand whether the quality of the service provided affects customer satisfaction and whether, consequently, a long-term relationship develops between the parties, reflecting on customer loyalty, trust, and commitment. Data collected from 107 client companies of consulting services were analyzed using the structural equation model and SmartPLS software. Results allow us to understand that the process's soft quality and the results' quality are the main determinants of customer satisfaction. The satisfaction derived from the quality of the consultancy service proves to be a great driver for the client of the consultancy relationship in terms of loyalty, trust, and commitment. This study uses the INDSERV model as a basis for quality analysis and includes several dimensions treated in other studies separately as determinants of satisfaction. It is suggested that managers promote the development of positive interactions during the service provided and facilitate the service alignment with the specific customer requirements. An empathetic attitude on the part of the consultants, advice adjusted to the client's needs, and the prompt resolution of any constraints allow an optimistic perspective about the consultancy firm, favoring the long-term relationship with the client.