Entrepreneurial firms are ubiquitous in our society and serve as indispensable drivers of economic growth, job creation, and technological advancement. It is well-accepted that joiners - early-stage nonfounding employees - are invaluable in these firms as they bring indispensable knowledge and experience. However, despite their vital role, we have little understanding of this group of entrepreneurial actors. In specific, our emerging knowledge on joiners is limited to two topics, namely 1) the defining features of joiners and 2) the recruitment of joiners. This is surprising as joiners and the entrepreneurial firm context are distinct from the dominant research context of established organizations, hence making theories and insights from traditional HRM research not readily applicable onto the joiner context. This project therefore focuses on providing insights into the informal mechanisms that guide joiners as well as increasing our understanding of the joiner employee experience. By means of three studies and a combination of qualitative and quantitative research methods, this project aims to break new grounds in the field of entrepreneurship and the emerging conversation on joiners. Furthermore, this project offers relevant practical insights to founders, joiners, and HR practitioners.