The rapid and global growth of bikesharing has come at a time when concerns for the environment are central in policy-making. It has, however, become apparent that the environmental benefits of bikesharing are at its best when bikesharing does not substitute walking, cycling or public transport and when it is combined with public transportation in covering the first and last mile of public transportation journeys. This thesis investigates how bikesharing is being integrated with public transportation in Oslo. To further understand the relationship between bikesharing and public transportation quantitative models were applied to address three knowledge gaps on the topic. Firstly, integrated use of public transportation and bikesharing on a trip-level tend to be the norm in studies. Results from this study show however that combined usage of public transportation and cycling in daily life is important in explaining membership choice. Secondly, previous studies usually view bikesharing members and non-members separately. Viewing these groups together has identified factors that affect interest in participating in bikesharing and factors that matter for actual membership. Findings suggest that environmental consciousness can explain interest in bikesharing, but membership choice is more likely to happen when urban characteristics and transportation in daily life makes it convenient. Finally, studies on integration between bikesharing and public transportation on trip-levels are often based on survey data or on bikesharing station frequencies. In this thesis it has been highly beneficial to use bikesharing population data on routes. Results indicate that bikesharing might serve an important integrational purpose with the metro- and railway- system in covering the first - and especially the last - mile of metro/railway journeys.