Over the last few decades there has been an increasing concern for studying the processes of technological capability accumulation in industrial firms of developing countries. From the evolutionary economics perspective, several works have focused on analysing the learning processes involved in building up a minimum base of technological knowledge to engage in innovative activities. Based on empirical work at firm-level, this literature has sought to build an analytical framework in order to explain the process of technological capability building. In this context, some taxonomies of technological capabilities have been developed. They include different stages of accumulation, from a minimum level of production capabilities (required for operating) the highest stage of advanced innovative technological capabilities. These taxonomies are a valuable analytical tool to help classify the technological activities and the level of capabilities reached by firms in each technical function. In this sense they allow to understand the depth of the accumulation processes by industrial firms. However, we argue that these taxonomies alone provide a limited understanding about the characteristics of the technological capability building process, the differences in the levels between technical functions, and the profiles of technological capabilities by industrial sectors and type of firms. The aim of this paper is to contribute to this discussion. First of all this paper describes the taxonomy of technological capabilities proposed by Bell and Pavitt (1995), which sums up the previous contributions in this direction. This taxonomy is then used to analyse the level of technological capability accumulation of three Mexican firms. Based on this empirical evidence, this paper discusses the scope of this analytical framework to examine the level of technological accumulation in developing countries firms.