Stage 1 Registered Report: http://dx.doi.org/10.23668/psycharchives.14372The rapid expansion of online sports betting has raised concerns about its potential impact on individual health and public health. In order to further develop etiological models for gambling disorder (GD) in sports betting, it is essential to unravel the underlying causal processes. Recent studies have identified risky online gambling behavior as an early indicator of GD. This study focuses on impulsivity as a well-documented risk factor for GD and investigated whether increased impulsivity leads to risky online gambling behavior and subsequently contributes to GD. Impulsivity, risky gambling behavior, and GD symptoms were assessed three times at three month intervals using a longitudinal cross-lagged panel design. We recruited a final sample of n = 427 regular sports bettors from the online gambling provider Tipico. Impulsivity and GD were assessed using a combinationof online experimental tasks and questionnaires. As a measure of risky gambling behavior, Tipico provided playertracking data for all participants. Random intercept cross lagged panel models were used to test the evidence for our hypotheses. Results showed partial support for the role of impulsivity in the development of GD, particularly through facets such as impulsive choice and certain impulsive personality traits. However, the findings suggest that impulsivity does not directly predict risky betting behavior, nor does such behavior mediate the relationshipbetween impulsivity and GD severity. These results emphasize the complexity of pathways to GD, highlighting the need to explore multifactorial models incorporating emotional, cognitive, and environmental mediators.