It is surprising how little we know about the relationships that matter to emerging adults, and we propose research to bridge that gap. First, we will ask emerging adults to generate a list of the individuals who matter. The list will be submitted via open‐ended text that we will code for relationship type. Our first aim is to gain information about the frequency and diversity of relationships that matter to emerging adults. We hypothesise that participants who list more relationships will have better well‐being and less loneliness. Second, we will use an adapted version of the Mattering Scale to assess how much specific relationships matter to participants by asking them to focus on five common close relationships (i.e., mother figures, father figures, romantic partners, best friends and closest‐in‐age sibling). For each relationship that exists for the participant, how much each relationship matters will be measured. We hypothesise that failing to mention a specific relationship in the open‐ended portion of the study will be related to lower perceived mattering of that relationship when participants report on mattering. Finally, we hypothesise that when specified relationships matter more to an individual, they will have less loneliness and better well‐being.