Background <p>Environmental health studies frequently measure levels of harmful chemicals in people or personal spaces, and returning those individual levels is an ethical responsibility and important opportunity to teach people about chemical exposures and how to reduce them.</p> Objective <p>We sought to enhance meaningful report-back by quantitatively evaluating a personalized tutorial designed to support environmental health literacy about personal chemical exposures.</p> Methods <p>We developed a novel smartphone-based tutorial that used the Predict-Observe-Explain educational framework to increase understanding of personal results graphs and promote taking actions to lower exposure. We deployed the tutorial as part of report-back in the Illinois Kids Development Study and Chemicals in Our Bodies pregnancy cohorts, and we collected digital analytics on how participants (<i>n</i> = 295) interacted with it. We tested the effect of the tutorial on participants’ accuracy at answering four graph-reading questions and examined differences by educational attainment and socioeconomic status. The tutorial prompted participants to select exposure sources that were relevant to them, and we calculated response frequencies of participants’ self-reported interest in taking related actions.</p> Results <p>A total of 92% of participants (<i>n</i> = 270) completed the Predict and Observe phases of the tutorial. Among those participants, 70% (<i>n</i> = 188) correctly answered all four graph-reading questions on their first attempt (without tutorial assistance), and success increased to 96% (<i>n</i> = 258) after the tutorial provided feedback and participants could make a second attempt. Improvement was greatest among participants without a bachelor’s degree. Participants who answered the Explain phase (<i>n</i> = 182) expressed high interest in trying new behaviors to reduce exposure.</p> <p></p> Significance <p>While most participants understood their personal exposure graph without assistance, the tutorial successfully reduced differences in understanding by educational attainment. The tutorial was also effective at creating intentions to adopt health-protective behaviors. Scalable tools like this can support effective report-back in populations with all levels of environmental health literacy.</p> Impact <p>To help people at all educational levels learn about their chemical levels and how to reduce them, we developed a personalized tutorial for use in reporting back results in environmental exposure studies. Before tutorial assistance, participants without a bachelor’s degree had lower understanding of their personal results graphs. Tutorial assistance successfully reduced differences in understanding between those with and without a bachelor’s degree. In addition, the tutorial was effective at creating intentions to adopt health-protective behaviors based on personalized recommendations for each participant. This scalable digital tool supports understanding and action during report-back of chemical exposure results.</p>