Many mothers do not communicate with their adolescent about sexual health topics due to perceived barriers. Our goal in this study was to shed light on the activities mothers engage in to prepare for sexual health discussions with their young adolescents. We also examined the extent to which mothers' past sexual communication behaviour and intentions were associated with engaging in these activities and perceptions of their helpfulness. Participants were 244 mothers of young adolescents who completed surveys at two points in time separated by 6 months. Overall, 64% of the mothers had engaged in one or more preparatory activity but found doing so only somewhat helpful. More extensive past sexual communication and higher sexual communication intentions were associated with engaging in preparation activities and finding them more helpful. However, past communication was significantly associated with the likelihood of engaging in preparatory behaviours for mothers with low, average, but not high sexual communication intentions. The results point to the importance of strengthening mothers' sexual communication intentions and providing them with information about high-quality resources and/or a resource package as means to increase the likelihood that they will engage in activities that prepare them to discuss sexual health topics with their adolescent.