Abstract
In this study we observe the daily work of nineteen software developers of a large Italian manufacturing company for a period of ten months to determine the effects of pair programming on the use of tools. Fifteen developers are existing team members and four have recently joined the team. They practice Pair Programming spontaneously, that is, when they feel it is needed. We identify the tools the developers use, how they distribute their time among these tools when working alone and when doing Pair Programming. The data have been extracted non-invasively by means of PROM - tool for automated data collection and analysis. The preliminary results indicate that developers working in pairs devote significantly more time to programming activities than developers working alone