Objective. The study evaluated the effects of a pros enhancing intervention on intention to uptake cervical cancer screening. It was hypothesized that the pros enhancement session (compared to an education session) would affect intentions of preintentional women, whereas it was expected to have negligible effects among women in intentional and actional stages of the health action process approach (HAPA). Thus, we tested the HAPA using stage‐matched and stage‐mismatched interventions. Further, a change in decisional balance was assumed to mediate the relationship between the group assignment and intention, with age acting as the moderator.Design and methods. Respondents (1,436 women, aged 18–60) were randomly assigned to either the intervention or control condition and filled out questionnaires before and directly after the manipulation (in one web‐based session).Results. Direct effects of the group assignment were observed only among preintentional women. Across the stages, however, change in decisional balance mediated the effects of the group assignment on the intention to uptake screening. Further, among participants in the preintentional stage, this mediation became significant only for women aged 35 or older.Conclusions. Although direct effects are in line with stage assumptions of the HAPA, meditational analysis among pre‐ and post‐intentional women indicated that similar processes accounted for post‐manipulation intention. Future research testing stage models should account for the mediating processes, which explain the effect