Gambling disorder and substance use disorders (SUD) overlap in terms of etiology and diagnostic constructs (e.g., preoccupation, loss of control), yet diagnostic thresholds for the disorders are different. Currently, endorsing 2–3 gambling disorder criteria does not warrant a diagnosis while endorsing 2–3 SUD criteria does. The aim of this study was to examine whether subclinical gamblers (i.e., endorsing 2–3 gambling disorder criteria) experience psychosocial dysfunction equivalent to individuals who are diagnosed with mild severity SUD (i.e., 2–3 SUD criteria) and whether this level of dysfunction is significantly different from individuals with no psychopathology. Data are from the first wave of Quinte Longitudinal Study, a large epidemiological sample (N = 4121). Psychometrically supported measures assessed for psychosocial functioning and the presence of Axis-I psychiatric disorders. Cross-sectional analysis examined 7 domains of psychosocial functioning using ANCOVA, which allowed for the inclusion of covariates, to test for difference between subclinical gamblers and individuals with no psychopathology and individuals with mild severity SUD. Equivalency testing compared subclinical gamblers in relation to mild severity SUD. Subclinical gamblers reported significantly poorer psychosocial functioning in relation to individuals endorsing no current psychopathology. Subclinical gamblers were also equivalent to and not significantly different from individuals with mild severity SUD. Subclinical gamblers experience similar psychosocial impairment to those individuals who endorse mild severity SUD, and this significantly differed from healthy individuals. The threshold for diagnosis of gambling disorder therefore warrants re-examination.