Short-term stability in adolescents' self-reported friendship networks was examined as a function of (1) participants' gender, (2) friendship status (best vs. secondary), (3) friendship gender composition (same sex vs. opposite sex), and (4) friendship contexts (school only vs. nonschool only vs. multiple). Adolescents (N = 102) took part in five monthly telephone interviews in which they nominated their friends and provided specific information for each of them. Results indicated that on average, one-third of participants' nominated friendships in their network were unstable over five months, with girls' perceived networks being more unstable than boys. Best friendship choices were more stable than secondary ones. Girls' reports of their opposite-sex friendships were more unstable than boys', and multicontext friendships (school and nonschool) were more stable than single-context friendships (school only or nonschool only). Results are discussed by highlighting the contribution of short-term assessments in understanding how adolescent networks change over time. (Contains 3 tables.)