Effectance—the basic positive experience of causing effects—provides a promising explanation for the enjoyment derived from novel low-challenge game genres featuring ample ‘juicy’ feedback. To date, game researchers have studied effectance using a little-validated 11-item scale developed by Klimmt, Hartmann, and Frey. To test its dimensionality and discriminant validity, we conducted an online survey (n = 467) asking people to report on effectance and related experiences in a recent play session. Confirmatory and exploratory factor analyses show poor fit with a unidimensional factor structure and poor discriminant validity with common enjoyment and mastery/competence measures, likely due to reverse-coded items and a separable input lag factor. We discuss further possible validity issues like questionable content validity, advise against using the scale in its present form, and close with recommendations for future scale development and use.