The current dissertation reports the results of a study that investigated how social interactions conducted through information and communication technologies (ICTs) impact subjective well-being. Prior research has found conflicting evidence on the influences of ICT use on well-being, with findings pointing to both negative and positive outcomes. Drawing from a theoretical framework that combines self-determination theory and the interpersonal process model of intimacy, this study investigated how technological affordances present in different ICTs influence social interactions and well-being. The main findings of this study point to the importance of investigating specific communication processes that occur on ICTs, such as self-disclosure, perceived responsiveness, and satisfaction of psychological needs. By analyzing data from 5037 social interactions that were captured using an experience sampling method, this study found that different technological affordances were associated with changes in interaction processes, which had implications for levels of relatedness need satisfaction and consequent changes in affective well-being.