Objective: There has been little research evaluating the best time to deliver prompts to support cognitive interventions, which may influence prompt effectiveness. This study examined whether context-aware transition prompting (prompting an individual during task transitions) is more effective than traditional time-based prompting. Method: Participants were 42 healthy adults who completed 12 different everyday activities, each lasting 1–7 minutes. Participants were tested in an experimental smart home testbed using prompts from an electronic memory notebook, which asked them to record the completed activities. Half of the participants were delivered prompts during activity transitions, while the other half received prompts every 5 minutes. Participants had the option to respond to the prompts and, if they did not respond to the initial prompt, a secondary prompt was administered. Participants also completed several Likert-scale ratings regarding their perceptions of the prompting system. Results: Results revealed that participants in the transition prompting condition used the notebook more frequently, as evidenced by a higher response rate, t(40) = 2.759, p = .009, and fewer secondary prompts, t(40) = 4.793, p < .001, when compared to the time-based prompting condition. Furthermore, participants in the transition prompting condition rated the system as more convenient, natural, and appropriate compared to participants in the time-based condition, ts < 3.9, ps < 0.001. Conclusion(s): Our findings suggest that prompting during activity transitions produces higher adherence and more positive perceptions of the prompting system. This is an important finding given the benefits of prompting technology and the possibility of improving cognitive interventions by using context-aware transition prompting.