This is the experimental data for the study investigating the acquisition of adjectival gender agreement in monolingual and bilingual Latvian- and Russian-speaking children. We have investigated five groups of participants: monolingual Russian three-year-olds, monolingual Russian four-year-olds, monolingual Latvian three-year-olds, monolingual Latvian four-year-olds and bilingual Latvian-Russian pre-schoolers. Pending the publication of the results, please contact the authors for the detailed description of the methodology.