Purpose: to develop and validate the content of an intervention plan for adolescents and young adults with Trisomy 21, focusing on vocabulary, working memory, and syntactic awareness. Methods: a methodological study with validation stages for the proposed intervention, which was assessed by ten judges. The content validity index was used to evaluate the content, quantitatively. Results: most judges had a doctoral degree. All propositions reached the minimum score. The oral language intervention plan focusing on vocabulary, working memory, and syntactic awareness was designed for adolescents and young adults aged 13 to 25 years and 11 months. The proposal included fifteen 40-minute weekly sessions. Conclusion: the study presented the process of developing and validating the Oral Language Therapy Plan, focusing on vocabulary, working memory, and syntactic awareness for people presented with trisomy 21, with the judges’ agreement.