The purposes of this study were to determine the dimensionality of the revised UCLA Loneliness Scale for adolescents through factor-analytic techniques, and to provide construct validity for the instrument by testing four theoretically derived hypotheses in 333 adolescents, ages 12 to 21. Using a prior criteria, a two-factor structure, resulting from a principal components analysis with an orthogonal rotation, best represented the dimensionality of the instrument for adolescents. The two factors demonstrated acceptable coefficient alpha reliabilities. Evidence of construct validity for the total scale was provided by three statistically significant correlations found be264tween the scale and the theoretically relevant variables of future time perspective, close friend solidarity, and dependency. Contrary to expectation, slow tempo was not appreciably related to loneliness. The results support the use of the revised UCLA Loneliness Scale in future research concerning loneliness in adolescents. ©1995 John Wiley & Sons, Inc.