This dissertation looks at how individual decisions are affected by group dynamics and social networks in a variety of settings. The first chapter examines the effect of social networks in labor markets by specifically asking what type of friend is most likely to help an individual find a new job. The second chapter uses a lab experiment to compare two methods to encourage socially optimal provision of a public good. The third chapter looks at the specific public good of parental volunteering at a child's school and disentangles whether parents' choices to volunteer are motivated by public or private benefits