This study examined whether style or intensity of child-focused intervention had a secondary effect on parental sense of efficacy and whether these effects varied by baseline level of parent stress. We randomized 87 children with autism, age 13-30 months, into one of four conditions: 15 versus 25 intervention hours crossed with 12 months of Early Intensive Behavioral Intervention versus Early Start Denver Model. Baseline parent stress was the putative moderator. Parent sense of efficacy, collected at baseline and the end of treatment, was the dependent variable. Analyses used generalized linear mixed model with full information maximum likelihood estimation. We tested main effects and interactions involving time, treatment intensity and style, and baseline parent stress to test moderation effects. Changes in parent efficacy across 12 months were related to intervention intensity but not style; this effect was moderated by level of parent stress at baseline. Parents with higher stress at the beginning of a 1-year, home-based, comprehensive intervention program had a higher sense of parenting efficacy if their child received lower intensity intervention; parents with lower stress at baseline had a higher sense of efficacy if their child received higher intensity intervention.