Cannabis is an increasingly sought-after remedy for US children with intractable (biomedically uncontrollable) epilepsy. However, like other complementary-alternative medicine (CAM) modalities, and particularly as a federally illegal, stigmatised substance, it is unsanctioned by mainstream medicine. Parents are largely on their own when it comes to learning about, procuring, dispensing, and monitoring treatments. Exploring how they manage is crucial to better assist them. Moreover, it can illuminate how ‘research’ done on the ground by laypeople variously disrupts and reinforces lay-expert and science-non-science divides. To those ends, in 2016, 25 Southern California parents who used, had used, or sought to use cannabis pediatrically for epilepsy/seizures were interviewed regarding their evidentiary standards, research methods, and aims when trying the drug. Parents generally described their work as experimentation; they saw their efforts as adhering to authorised scientific practices and standards, and as contributing to the authorised medical cannabis knowledge base. Findings subverted assumptions, based on an outdated stereotype of CAM, that cannabis-using parents do not believe in biomedicine. Indeed, parents’ desire for their children’s biomedical demarginalisation, combined with biomedical dependency and a high caregiver burden, fuelled a collaborative stance. Implications for understanding the boundaries of science are explored, as are norms for parent agency as ill children’s care managers, radicalisation among people affected by contested illnesses, and the future of ‘medical marijuana.’