Drawing on lifestyle-routine activity theory, this dissertation explores associations between everyday life, crime, and fear of crime among adolescents and young adults. It also examines the operationalisation of the concepts of lifestyle and routine activities, and explores the use of experience methods, via a smartphone application named STUNDA, to collect data about everyday life. Of the four studies conducted, Study I shows that different specific lifestyle measures are of varying relevance for victims, offenders, and victim-offenders, which indicates that no single universal lifestyle feature is of relevance for all outcomes studied. The findings from Study II reveal that spending time with friends in the city-centre is associated with lower levels of fear of crime across months, days, and moments. However, other associations between everyday life variables and fear of crime are inconsistent across these reference periods. Study III, a systematic review of the literature, shows that measures of lifestyle and routine activities differ in the frequency with which they are used in studies on interpersonal victimisation and offending. Illegal activities are often used as lifestyle/routine activity measures in studies on victimisation while unstructured and peer-oriented activities dominate in studies on offending. However, the measures used in the included studies are diverse, which indicates that researchers use a wide range of activities that are intended to measure lifestyle/routine activities. The final paper, Study IV, explores fear of crime in relation to moments of everyday life and finds that specific features of settings, such as being in semi-public and public spaces and on public transport, increase the odds for experiencing fear of crime. The overall conclusions of the studies point to methodological and theoretical directions for future research. First, research in the field of lifestyle-routine activity theory needs to consider specific and potentially different activities when examining victimisation, offending, and the overlap between these two outcomes. Further, fear of crime research must consider different reference periods, such as months, days and moments, since fear may not only be defined as a more stable trait-like phenomenon but also as a momentary and transitory experience in everyday life. The types of measures used to represent everyday life also require consideration, particularly in terms of the inclusion of lifestyle/routine activity measures that are actually related to criminogenic exposure. For theory more specifically, the implications of the findings point to an overall confirmation of the view that exposure to various environmental circumstances is associated with crime and fear of crime. However, across all of the studies conducted, the findings point to potential weaknesses of the theory. In particular, the lack of an elaborated perspective on individual traits and characteristics limits the explanatory scope of lifestyle-routine activity theory. For instance, people with similar lifestyles still vary in terms of their victimisation, offending, and fear of crime, which necessitates the inclusion of additional individual-level factors that could explain these variations. Future research must thus either modify lifestyle-routine activity theory or open up for other theoretical perspectives that provide a more holistic approach to understanding the role of both environ-mental and individual factors when studying everyday life, crime, and fear of crime.