Problematic usage of the internet (PUI) describes maladaptive use of online resources and is recognized as a growing worldwide issue. Here, we refined the Internet Addiction Test (IAT) for use as a screening tool to measure generalized internet use problems in normative samples. Analysis of response data with parametric unidimensional item response theory identified 10 items of the IAT that measured most of the PUI latent trait continuum with high precision in a subsample of 816 participants with meaningful variance in internet use problems. Selected items may characterize minor, or early stages of, PUI by measuring a preoccupation with the Internet, motivations to use online activities to escape aversive emotional experiences and regulate mood, as well as secrecy, defensiveness, and interpersonal conflict associated with internet use. Summed scores on these 10 items demonstrated a strong correlation with full-length IAT scores and comparable, or better, convergence with measures of impulsivity and compulsivity. Proposed cut-off scores differentiated between individuals potentially at risk of developing PUI from those with few self-reported internet use problems with good sensitivity and specificity. Differential item function testing revealed measurement equivalence between the sexes, Caucasians and non-Caucasians. However, evidence for differential test functioning between independent samples drawn from South Africa and the United States of America suggests that raw scores cannot be meaningfully compared between different geographic regions. These findings have implications for conceptualization and measurement of PUI in normative samples. (PsycInfo Database Record (c) 2021 APA, all rights reserved).