Considerable policy and research efforts have been directed at fostering the growth of small high technology firms to encourage growth. Part of that growth is commercialisation, particularly in the high–technology sector. This study illuminates the relationship between the commercialisation process and business growth in that sector. Case studies of small, knowledge–intensive business services firms show that firm–related growth follows a phased route associated with particular activities in the commercialisation process, and furthermore, that for small firms the challenges of commercialisation may jeopardise their growth. However, the study also reveals that successful commercialisation may beget relatively high levels of firm growth.