Collaborating with a client-partner during new service development (NSD), a phenomenon seen more and more often, has certain advantages for the industrial services provider. Among them is the ability to reduce risk of service failure by developing the new service to meet the client-partner's specific needs, sharing NSD costs, and gaining access to specific client expertise not found in-house. There are, however, certain hazards to performing NSD with a partner firm. Not only must the service provider master and manage the NSD process, but also the client relationship as it evolves throughout the NSD process. Indeed, a large part of a successful new service outcome depends on a solid relationship between supplier and client, since many industrial services require on-going interaction between the two parties long after the new service is in production. One of the most effective tools available to the service provider to manage the client relationship is Relationship Marketing. Relationship Marketing (RM) is a process by which the service firm builds an excellent relationship with the client firm based on mutual trust and motivates the client to commit to the relationship over the long term. Through the use of case study analysis, this research identifies a "best practices" list of Relationship Marketing activities that a service provider can use throughout the different collaborative NSD phases. When implemented, the best practices boost the likelihood that the client will be satisfied with its relationship with the service provider, and ultimately, satisfied with the new service.