The perspective of environmental psychology is particularly valuable for understanding why individuals create new organizations that pursue sustainability targets (sustainable entrepreneurship) (Shepherd & Patzelt, 2011) or renew existing organizations and business models (sustainable intrapreneurship). In this chapter, we explore how individuals negotiate and align their private sustainability concerns with their working roles and if this leads to sustainable intra-or entrepreneurship, or to other types of pro-environmental behavior (PEB) at work. In this respect, we focus on spillovers of PEB between private and public spheres to the working sphere as a source for sustainable intra-and entrepreneurship. Spillovers occur when one PEB has a positive or negative effect on a person’s subsequent PEBs (Thøgersen, 1999; Truelove, Carrico, Weber, Raimi & Vandenbergh, 2014). Based on in-depth interviews with 25 individuals, we explore spillover effects from private and public sphere PEBs to work sphere PEBs (life-work spillover effects) with a specific focus on sustainable intra-and entrepreneurial activities: Do individuals who installed a photovoltaic system at home (private PEB) in their role as employees also seek to introduce renewable energies at their companies? Is a member of a non-governmental organization for environmental protection (public PEB) more likely to establish a new sustainability-oriented business than somebody who has no public commitment to sustainability issues? Our overall research question is: Is there a potential in the life-work spillover of private and public sustainability involvement for sustainable entre-or intrapreneurship at work? On the basis of our qualitative study, we develop a typology of spillover processes and show that sustainable intra-and entrepreneurship, as well as other forms of PEB at work, is influenced by individuals’ environmental activities in private and public spheres. We show that people who are characterized by a relatively high degree of personal involvement in sustainability issues are more likely to engage in sustainable intra-and entrepreneurship than people with a

relatively low degree of personal involvement. Those individuals who show the highest degree of involvement at work are also strongly engaged in public PEB and/or driven by the motivation to make their contribution to sustainability. Individuals who are largely driven by the motivation to save money are more focused on technologically oriented PEB in the private and work sphere (e.g., using technologies for increasing energy efficiency) and are not active in public PEB. We further explore different ways of dealing with organizational barriers that generate tensions and hinder intrapreneurial activities inside existing organizations as well as strategies that employees use to overcome them. The next section provides an introduction to the literature on sustainable intra-and entrepreneurship and life-work spillover of PEB. In the following section, we report results from qualitative research on 25 individuals and their ways to align their pro-environmental and sustainability behavior at home and at work. Our research enables us to identify different types of PEB spillover effects that are connected with behavioral strategies and motivational orientations towards sustainable entre-or intrapreneurship. In this way, we extend research on sustainable entrepreneurship by focusing on private and public sphere PEBs as “learned” behavioral strategies which can serve as a source for innovative forms of PEB at work or for sustainable intra-and entrepreneurship. On the basis of our findings, employers are encouraged to discover and understand the private and public engagement of environmentally conscious employees in order to release the motivational potential of their work force for the energy transition in their companies.