This study constructed a questionnaire, named "Lifestyle Change in Regard to Problematic Internet Use (LC-PIU)," for helping school psychologists detect early indications of PIU-related lifestyle changes in university populations. Our focus is on all university students who use the Internet, not users who already show dependent symptoms. The lifestyles that we concerned include physical/social activities and dietary/sleep patterns that are notable consequences of excessive Internet use (Lam et al., 2009; Choi et al., 2009). With 708 university students recruited in 2009 (Time 1), we tested the factor structure of LC-PIU and determined the concurrent and cross-year predictive utilities with the same participants in 2010 (Time 2). The 2009-sample was randomly split into two independent subsamples for calibration and validation using exploratory and confirmatory factor analyses. The calibration and validation results, along with convergent and discriminant tests, confirmed that the LC-PIU is composed of five distinct subscales: problematic Internet use, physical activity change, social activity change, dietary pattern change, and sleep pattern change. All Time-1 LC-PIU subscores were positively correlated with depression, loneliness, and weekly Internet use at Time 1 and Time 2. Only a negative correlation was found between gender and social activity change at Time 1 and Time 2. (Contains 1 table and 1 figure.)