Most authors agree that commitment is an important building block in long-term business relationships. This study attempts to investigate how commitment develops in long-term business-to-business relationships in the context of an international quality network. To accomplish this objective, the relationship marketing perspective and the network perspective are integrated into a conceptual framework, describing how network constructs influence the long-term relationships indirectly through commitment. This framework was tested empirically in the context of the European cement industry with regards to a total quality management network. Our results indicate that, in particular, a ective commitment and calculative commitment have a significant positive e ect on the parties' willingness to invest in the relationship. The antecedents of commitment, and especially actor bonds, have an indirect influence on the willingness to invest in the relationships.