The "1,2,3,emoció!" is a universal preschool program of emotional education for children aged 3-5 years that has positive effect on emotional competence. The objective of this study was to evaluate the effectiveness of this program specifically in 3- to 5-year-old children with autism spectrum conditions. The effectiveness was evaluated during the first year of implementation (school year 2018-2019) in Barcelona. We conducted a cluster randomized community trial, with schools as units of randomization. The children's level of emotional competence was evaluated with the validated Emotional Competence Assessment Questionnaire (score range from 30 to 180). We designed a linear regression model for paired measures. The dependent variable was the final Emotional Competence Assessment Questionnaire score adjusted by the initial score, sex, and grade. The sample consisted of 49 children with autism spectrum conditions, of which 11 were girls. Children in the intervention group showed an increase from the initial score to the final score that was almost three times higher (16.1) than the increase observed in children in the comparison group (6.6). The difference between the two groups was statistically significant, with 8.9 points (95% confidence interval: 1.2-16.6) attributed to the intervention. We conclude that the "1,2,3,emoció!" universal program has the potential to be effective in children with autism spectrum conditions.