The epidemic of child abuse in the U.S. (>670,000 confirmed annually) causes massive harm to children and the adults they become. Surprisingly, <1% of these substantiated cases of child abuse are identified and reported by early childhood professionals (ECPs) –despite the fact that ECPs take care of >10 million American children, and that infants and toddlers account for >75% of all deaths related to child abuse. Results from our parent randomized controlled trial show that the online iLookOut for Child Abuse (iLookOut) Core training significantly improves ECPs' knowledge and attitudes about child abuse/reporting (effect size=1.09 and 0.66, respectively). Preliminary data from this trial also suggest that (compared to standard training) iLookOut improves ECPs' actual reporting of suspected abuse: i) reports are more likely to be screened-in for investigation by child protection services (86% vs 70%, p<.001), and ii) these screened-in reports are more likely (56% vs 34%, p=.001) to be “high yield” (ie, child abuse is identified and/or social services are recommended). But we know that for gains to be sustained, they must be reinforced …and reinforced again. This is because newly acquired knowledge and habits decay over time unless they are kept in use. Built into the design of our parent study was an exploratory effort to deliver basic, ad hoc follow-up messaging to maintain awareness and promote knowledge retention after completing iLookOut's Core training. But it was beyond the scope of the parent study to fully develop this follow-up intervention, study its impact, or establish its optimal timing. Through several small grants, we built a research-quality platform to deliver brief (5-10 minute) gamified micro- learning activities that reinforce and augment what is taught in iLookOut's Core training, and provide practice opportunities to apply what has been learned. We have piloted this micro-learning in the parent study and shown that ECPs will complete these activities on their smart phones in return for 3 hours of (no cost) professional development credit. This, along with strong evidence for the efficacy of iLookOut's Core training, now positions us to systematically examine how interactive, gamified micro-learning promotes knowledge retention and fosters behavior change (regarding child abuse and its reporting), and to establish that its implementation is feasible. Just as rigorous research is needed to determine the optimal timing to give booster doses of vaccines to bolster a child's immunity, it is likewise essential to understand the optimal timing for administering iLookOut's micro- learning so as to boost ECPs' waning knowledge/preparedness to protect children from abuse. Using validated measures, self-report, and data from state child protection services, this study will 1) measure the rate of knowledge decay following iLookOut's Core training, 2) examine how well micro-learning activities (delivered at variable time points) promote k...