Preschoolers who display extremely inhibited behavior are at risk for the development of anxiety disorders. However, behavioral inhibition (BI) is a multifaceted characteristic. Some children with BI are fearful when confronted by unfamiliar adults, peers, and objects; others are fearful when separated from their parents. In the present study, we examined specific features of BI that predicted observed friendship formation among preschoolers who are behaviorally inhibited. We also examined whether teacher ratings of classroom behaviors predicted friendship formation. Sixty highly inhibited children (35 female, M[subscript age] = 52.57 months) were observed during eight weekly free-play sessions with initially unfamiliar inhibited peers. Free-play periods occurred before weekly intervention sessions for children with BI and their parents. An observational protocol was developed to identify children who made a friend during the eight weekly sessions. Before the first session, different subtypes of BI were assessed by parents; preschool teachers assessed the children's classroom behaviors with familiar peers. Twenty-six children met the criteria for having made and kept a friend. Probit regression analyses revealed that parent ratings of BI among unfamiliar peers and teacher ratings of children's social anxiety before the intervention were associated with a decreased probability of making a friend. No evidence was found linking children's responses to the intervention and friendship formation. Results suggest that extremely inhibited preschoolers are capable of making friends. Implications for future research and intervention efforts that focus on individual differences of children with BI are discussed.