The current study examined the dimensions of Emerging Adulthood (EA) and specific self and social processes that influence the experience of this important transitional developmental period, with a particular focus on identity exploration. A large sample collected from a multi-institution collaboration was examined. Results indicated that Arnett's EA key dimensions (identity exploration, feeling in-between, self-orientedness, negativity/instability, and experimentation), plus an exploratory dimension, other orientedness, shift as a function of age and analyses of quadratic effects suggest that some dimensions may characterize EA better than others. In addition, perceptions of others' regard (and not self-esteem) moderated the relationship between age and identity exploration. Findings support Arnett's theory, but also suggest that interpersonal factors are more influential than intrapsychic in prompting identity exploration during EA.