This article assesses the utility of the Index of Problematic Online Experiences (I-POE) in a national sample of adolescents in the United States. The study was based on a cross-sectional national telephone survey of 1560 Internet users, ages 10 through 17. Data were collected between August, 2010 and January, 2011. The I-POE is an 18-item binary response index which can be used to assess problematic internet use across multiple behaviors and activities. Exploratory and confirmatory factor analysis supported a revised index with two factors: a 9-item "excessive use" scale and a 9-item "online social and communication problems" scale among this population. The I-POE showed favorable psychometric properties including adequate internal consistency for the overall scale and for the two subscales. Scores correlate with offline emotional and behavioral difficulties and the I-POE could have value for use as a part of broad mental health assessment procedures in clinical or school settings.