There has been a proliferation of software engineering standards in the last two decades. While the utility of standards in general is acknowledged, thus far little attempt has been made to evacuate the success of any of these standards. One suggested criterion of success is the extent of usage of a standard. In this paper we present a general method for estimating the extent to which a standard is used. The method uses a capture-recapture model that was originally proposed for estimating birth and death rates in human populations. We apply the method to estimate the number of software process assessments that were conducted world-wide between September 1996 and June 1998 using the emerging ISO/IEC 15504 international standard. Our results indicate that 1264 assessments were performed with a 90% confidence interval of 916 and 1895. The method used here can be applied to estimate the extent of usage of other software engineering standards, and also of other software engineering technologies. Such estimates can benefit standards (or technology) developers, funding agencies, and researchers by focusing their efforts on the most widely used standards (or technologies).