Based on a childhood intervention from ages 3 to 5 years that included additional fish consumption and which resulted in reduced schizotypal personality at age 23, we had previously hypothesized that omega-3 could reduce schizotypy. The current study tests the hypothesis that omega-3 supplementation reduces schizotypy in children. In this intention-to-treat, randomized, single-blind, stratified, factorial trial, a community sample of 290 children aged 11-12 years were randomized into Omega-3 Only, Cognitive Behavioral Therapy (CBT) Only, Omega-3 + CBT, and Control groups. Schizotypy was assessed using the SPQ-C (Schizotypal Personality Questionnaire for Children) at 0 months (baseline), 3 months (end of treatment), 6 months (3 months post-treatment), and 12 months (9 months post-treatment). A significant group × time interaction (P = .013) indicated that, compared with Controls, total schizotypy scores were reduced in both Omega-3 Only and Omega-3 + CBT groups immediately post-treatment (d = 0.56 and 0.47, respectively), and also 3 months after supplementation terminated (d = 0.49, d = 0.70). Stronger findings were observed for the interpersonal schizotypy factor, with both omega-3 groups showing reductions 9 months post-treatment compared with the CBT Only group. Schizotypy reductions were significantly stronger for those with higher dietary intake of omega-3 at intake. Sensitivity analyses confirmed findings. Results are unique in the field and suggest that omega-3 can help reduce schizotypal personality in community-residing children. From an epidemiological standpoint, if replicated and extended, these findings could have implications for early prevention of more significant schizotypal features developing later in adolescence. "Healthy Brains & Behavior: Understanding and Treating Youth Aggression (HBB)." ClinicalTrials.gov Identifier: NCT00842439, https://clinicaltrials.gov/ct2/show/NCT00842439.