In recent decades, technology has emerged as a beacon of hope to aid humanity in addressing two pressing issues of our time: human health and climate change. However, despite advances in medicine and climate technology, rates of infectious diseases (Jones et al., 2008) and carbon dioxide emissions (Olivier & Peters, 2020) continue to rise. Alongside technological and systemic regulations, it is also the behavior of each individual that contributes to curtailing infectious diseases and carbon dioxide emissions. Yet, individuals often struggle to align their good intentions with their actual behavior. This gap underscores the complexity of breaking ingrained habits and adopting new behaviors, demanding more than mere intention. The question of how to achieve behavior change in the context of health and climate change is not easily answered; it requires extensive interdisciplinary research. Information Systems research can support and advance the study of behavior change through digital interventions. Digital interventions, due to their availability and scalability, stand as promising tools for facilitating behavior change and research. The inclusion of measurement instruments within technological devices furthermore allows for the collection of real-world behavioral data. Consequently, Information Systems research can not only contribute but also enhance the empirical validation and expansion of behavioral theories. Despite the potential that Information Systems hold in the realm of behavioral research, it remains a domain far from being fully explored. The main objectives of this dissertation are to provide insights into the effectiveness of digital interventions in fostering healthy and environmentally sustainable behavior within the real-world context, alongside the empirical validation of behavioral and motivation theories. To accomplish this, the dissertation adopts an interdisciplinary approach encompassing two experimental field studies and one survey field study. The field studies are centered on behavior change in the realms of health and sustainability behavior among children and employees. The first two chapters revolve around the outcomes of two large-scale field experiments, investigating hand washing behavior of children in day care centers. Within Chapter 1, a digital intervention is designed and the applicability and effectiveness of the intervention are affirmed across day care centers in Finland and Germany. The data indicate that soaping time of children, a proxy for hand washing quality, can be improved by 62% while the digital behavior intervention is in place. In Chapter 2, the intervention subsequently serves as a tool to empirically validate and expand behavioral theory, specifically the Motivation Crowding Theory. The results provide empirical evidence for the efficacy of digital rewards in children. This underscores the value of digital rewards while disproving potential negative effects as suggested by the Motivation Crowding Theory. The findings of Chapters 1 and 2 underscore the effectiveness of digital behavior change interventions leveraging digital rewards both in research and in practice. The research undertaken in this context can serve as a blueprint for Information Systems researchers venturing into behavioral research, particularly with children. Moreover, it offers practitioners guidance for the design of effective and scalable systems tailored to children. Chapter 3 presents the results of a field study that examines the motivations of train drivers to use Green Information Systems in the workplace and thus to contribute to energy savings in the transportation sector. The results of the interviews and surveys conducted for this purpose confirm the applicability of the Protection Motivation Theory in the context of Information Systems. The collected data show that employees’ moti- vation to engage in climate-protective behavior depends on their perception of their own response efficacy and the severity of climate change. The identified motivations provide important starting points for the development of digital behavior interventions aimed at promoting environmentally friendly behavior among employees. Overall, this thesis illustrates that Information Systems can support human behavior change, and serve as a tool to measure and examine behavior change and underlying behavioral theories. The conducted field studies underscore the effectiveness of digital interventions in real-world settings. With the chosen interdisciplinary approach and a combination of different methods, existing behavioral theories are utilized in the field of Information Systems, empirically validated, and expanded. The research emphasizes that Information Systems have the potential to assist individuals in changing their health and sustainability behavior, addressing two pressing issues of our time.