Objective: Given participants’ research literacy is essential for clinical trial participation, evidence-based strategies are needed that improve literacy and easily accessed online. We tested whether an infographic letter–that illustrated how dropouts can distort study conclusions–improved participant knowledge about the impact of dropouts relative to a control letter. Method: In three distinct online samples purposely recruited to assess reproducibility, young ethnically diverse adults were randomized to read an infographic letter or control letter in a hypothetical scenario. Secondary outcomes included participants’ perceived transparency of the research organization, perceived value of retention, and perceived trust of the organization. We purposely included two discriminant items, perceived value for the trial outcome and keeping commitments in general, both hypothesized not to change. Results: Across samples, ∼20% more infographic participants correctly answered how dropouts affected study conclusions than control participants. For example (Experiment 3), nearly 90% of infographic participants correctly answered versus only two thirds of controls (88.7% vs. 66.7%, absolute percentage difference 22.0%, p < .0001). Infographic participants had substantially higher transparency, perceived value for retention, and trust (Cohen’s ds = 0.4–1.0, ps < .0001), yet importantly did not value the study outcome or report keeping commitments more than control participants (Cohen’s ds = 0.0–0.1, ps > .10). Conclusions: Promisingly, this transparent, visually powerful methodological infographic improved knowledge and trust. Future trials could embed and experimentally test whether such low-cost online infographics improve not only research literacy, but also trial retention, especially among populations with less initial trust about research.