Over the past 15 years, researchers, practitioners, and policy-makers have observed poor program usage of unguided e-mental health interventions in real-world settings. This paper proposes that focusing on the impact of program usage, however, distracts us from the mechanism of change that is linked with the targeted clinical outcomes: the incorporation of therapeutic activities. Uncovering this relationship is particularly important in digital mental health intervention research because the therapeutic activities meant to achieve beneficial outcomes are not always explicit. The paper presents a framework that may help disentangle different conceptual aspects in order to better investigate the relationship between user engagement with the digital program, therapeutic activities, and clinical outcomes. Critically, one of the main challenges involves determining whether the use of the digital program itself is tied to a therapeutic activity. Such a framework may enable a better understanding of how e-mental health interventions work and to better address intervention design failure points.