This study is a research into firm level innovation activities and the role of the engineers in R&D work. The innovation processes is tried to be explained as a mental labor process. With this aim, case studies are done within three companies in Turkey (one international and two local firms), which are professionally engaged in innovation activities in the automotive sector. A total of seven in-depth interviews are made with R&D engineers of the corporations. These interviews together with the participant observations constitute the empirical data. The analysis of research problematic is based upon these empirical findings.