This research proposes a model of Interorganisational Commitment (IOC). The model is based on six constructs and was tested on 99 small and medium sized firms. The model examines interaction and non-interaction between firms. The theoretical model suggests that firms enter relationships in sequences, where they first consider motives and partner preferences before interaction takes place. Later in the sequence more extensive interactions develop into committed relationships that have consequences influenced by Trust (TRU) and Reciprocity (RCP) perceptions, which influence and promote lasting IOCs. The tested model exhibits nomological, convergent and discriminant validity, as well as reliability