The current study investigates experiences of self-expansion after both positive and negative events within a romantic relationship and the potential impact of mindfulness on self-expansion outcomes. We hypothesized that individuals would experience similar levels of self-expansion, regardless of the valence of the event. We also hypothesized that individuals higher in mindfulness would report higher levels of self-expansion following a positive or negative event with their romantic partner. This study uses data from 316 individuals in a romantic relationship that were recruited from a subject pool. Multilevel modeling was used to conduct all analyses. Contrary to our hypotheses, individuals experienced greater self-expansion after a positive event with their partner, when compared to a negative event and higher mindfulness, scores did not predict increases in self-expansion.