In recent years, little research has considered how theoretical definitions of service relate to practice. The purpose of this study was to compare the definitions of service given by practitioners to the approaches presented in the service marketing literature. Based on a literature review, a framework was developed to illustrate changes in service marketing thinking. The framework was used to analyse empirical data, consisting of definitions of service presented by practitioners during thematic interviews conducted in Finland. The findings indicated that the practitioners’ definitions reflected the diverse theories presented in the service marketing literature. However, no firm evidence could be found that, for example, practitioners’ age, sex, or service sector would affect the definitions they gave. The findings indicated that both researchers and practitioners should be aware of the diversity of definitions. In companies, practical problems may be avoided by formulating well-structured common definitions.