In this article we show how the results from software process appraisals of ten small‐ to medium‐sized software development enterprises demonstrate that as companies become larger they naturally use an increasing number of practices within the Capability Maturity Model Integration (CMMI®). The companies involved in this study had no CMMI® experience prior to this work. We identify those practices that tend to be best followed by both small‐ and medium‐sized enterprises and those that tend to be introduced as the company size increases from small to medium. We conclude that the CMMI® appears to have an inherent roadmap for process improvement, buried within its explicit structure of capability levels that is driven by company expansion. The results of this study can be used by organisations to plan process improvement as they expand in size and staff complement. We further show how our results are consistent with the European Union's definition of a ‘Small’ and a ‘Medium’ sized enterprise. Copyright © 2009 John Wiley & Sons, Ltd.