Commitment in the internationalization process model (IP-model) is challenged by the search for knowledge through experience and interactions. Critics opposing this logic even forced the founder of the model to call for the need for integration of other elements in order to understand irregular behaviour like rapid internationalization, loss of commitment and market exit. Aligned with this call, the paper raises the question of how the IP-model can be applied to analyse both regular/incremental and irregular/non-incremental behaviour of the firms. To reach an answer, the paper proposes a theoretical view by adding expectation and unknown uncertainty to the IP-model and examines this in a case study. The contribution is a further development of the IP-model by merging these two concepts that provide tools for understanding irregular behaviour. The paper analyses a Swedish firm's internationalization in different foreign markets for the period of 1995-2009. Conclusions support the understanding of how the model can describe regular incremental and irregular non-incremental commitment behaviour.