Friends are an important source of well-being but people differ in who they consider to be friends. With a unique quantitative test of such differences based on 17,650 social relations of 706 Dutch women (aged 18–41), of whom 40% were considered friends, we examined (a) which kind of personal relations were typically identified as friends (e.g., family, colleague), (b) how this linked to relationship closeness, face-to-face and non-face-to-face contact, and (c) whether these relationship characteristics of friendships differed with age. Most friends were met at school (>70%) and 20% of family were considered friends. Friendships were often close relationships with more non-face-to-face contact, while meeting in person was less predictive. Relatively older women reported fewer friends. Even in this homogenous sample with multiple measures of tie strength, friendships were difficult to predict and often overlapped with other social roles, meaning that researchers should be careful in using friendship as distinct category.