The main objectives of this master thesis are to identify and analyze how the startup founders role changes during startup development and which factors drive these changes. After the review of available international literature, the interview method was chosen to receive a deep insight into the founders role development in tech startups. Interviews with founders in Europe and US were conducted, which showed that founders see their roles development as evolutional, but full of challenges. An empirical study confirmed that the acquisition of human, social and financial capital requires the attention of founders and balancing with multiple priorities. Hiring, delegation and building a culture within the team were emerging issues for the founders. They devote significant part of their time to those activities and sometimes even change the way of doing things and how they communicate with the team. The biggest supporters in those challenges were the founders own experience and advice from the founders community. Therefore, networking was identifies as an important driver for the founders development.