Self-disclosure is a powerful precipitant and enhancer of interpersonal relationships, but its contingents and mechanisms are still poorly understood. To address this gap, we examined the emotional and interpersonal consequences of self-disclosure online with a particular focus on the real dynamic nature of the interaction. In two large-scale experiments, 234 dyads of undergraduates participated in an online chat. The dyads' self-disclosure (positive vs. negative vs. no self-disclosure), anonymity (present vs. absent), and role (initiator vs. exposed) were manipulated. Participants' personality factors (self-criticism, experiential avoidance, openness to experience) were assessed prior to the interaction. Positive and negative affect were assessed prior and subsequent to the interaction, and willingness to interact again was measured as an outcome interaction. Positive disclosure resulted in an increase in positive affect and negative disclosure resulted in an increase in negative affect for both initiators and exposed participants. Personality predicted changes in affect in the self-disclosure condition, and also moderated affective contagion. Self-disclosed/anonymous participants were reluctant to meet their partners again, consistent with the "strangers on a train" conceptualization.