Studies have shown that nearly two-thirds of all software process improvement (SPI) efforts have failed or at least fell short of expectations. Commitment has been argued to play an important role in determining the outcome of an SPI endeavor. This paper reports preliminary results from a study that attempts to explicate commitment process in SPI. Four SPI efforts were studied in two different organizations using action research approach. A new model to study the evolvement of commitment through commitment nets is introduced. Results indicate that commitment process is about the arrival, existence and departure of a concern and action in actor's commitment net. Analysis and discussion of means used to transfer concerns at individual, group and organizational level is provided.