OBJECTIVE: To identify types of containers from which young children accessed solid dose medications (SDMs) during unsupervised medication exposures and the intended recipients of the medications to advance prevention. STUDY DESIGN: From February to September 2017, 5 US poison centers enrolled individuals calling about unsupervised solid dose medication exposures by children ≤5 years. Study participants answered contextually directed questions about exposure circumstances. RESULTS: Sixty-two percent of eligible callers participated. Among 4496 participants, 71.6% of SDM exposures involved children aged ≤2 years; 33.8% involved only prescription medications, 32.8% involved only over-the-counter (OTC) products that require child-resistant packaging, and 29.9% involved ≥1 OTC product that does not require child-resistant packaging. More than one-half of exposures (51.5%) involving prescription medications involved children accessing medications that had previously been removed from original packaging, compared with 20.8% of exposures involving OTC products (aOR, 3.39; 95% CI, 2.87-4.00). Attention deficit hyperactivity disorder medications (49.3%) and opioids (42.6%) were often not in any container when accessed; anticonvulsants (41.1%), hypoglycemic agents (33.8%), and cardiovascular/antithrombotic agents (30.8%) were often transferred to alternate containers. Grandparents' medications were involved in 30.7% of prescription medication exposures, but only 7.8% of OTC product exposures (aOR, 3.99; 95% CI, 3.26-4.87). CONCLUSIONS: Efforts to reduce pediatric SDM exposures should also address exposures in which adults, rather than children, remove medications from child-resistant packaging. Packaging/storage innovations designed to encourage adults to keep products within child-resistant packaging and specific educational messages could be targeted based on common exposure circumstances, medication classes, and medication intended recipients.