Studies on the inclusion of non-warring parties in peace agreements have risen significantly in the research community. Focus has mostly been on civil society and women’s inclusion while youth inclusion has rarely been studied. At the same time, in 2015, the United Nations Security Council adopted resolution 2250 on youth, peace, and security arguing that youth can contribute to lasting peace. However, this statement has not been substantiated with evidence of this relationship. This paper will therefore study the relationship between meaningful youth inclusion in peace agreements and vertical legitimacy, the people’s belief in the government’s right to rule. Using a comparative case study, the suggested hypothesis, that meaningful youth inclusion will lead to higher vertical legitimacy is tested in Colombia and Guatemala. The results do not find support for the theory. Meaningful youth inclusion in the Colombian peace agreement did not lead to a higher vertical legitimacy later. Of note is that there was limited information available for Guatemala which is a big problem for the study as I cannot estimate the change in vertical legitimacy and thus not draw any certain conclusions from the study. More research should therefore look further into this theory using field research.