Youth suffrage is the right to vote for young people. It forms part of the broader universal suffrage and youth rights movements. Most democracies have lowered the voting age to between 16 and 18, while some advocates for children's suffrage hope to remove age restrictions entirely.

According to advocates, the "one man, one vote" democratic ideal supports giving voting rights to as many people as possible in order for the wisdom of a more representative electorate to create better outcomes for society. Advocates suggest that setting a voting age at or below 16, would accomplish that goal, while also creating a more ethical democracy for those who believe that those most impacted by government decisions (those with the longest life expectancy) are given at least an equal say in decision-making.

The idea of presumptive inclusion holds that individuals should be given the right to vote by default and only removed if the government can decisively prove why someone shouldn't have that right. Erring on the side of over-inclusion also checks the temptations of those with power (or simply status quo bias) to exclude capable voters. The first reason for exclusion that is seen as legitimate by some democratic theorists is competence, while the second is connection to the community. Age-related debates fall under the question of competence.

Many countries don't require literacy in order to vote, validating the idea that attaining a certain level of education is not needed to understand how to cast a vote according to one's interest or beliefs. In the 1965 U.S. Voting Rights Act for example, it was determined that a 6th grade education (typically achieved by age 12-13) provided "sufficient literacy, comprehension and intelligence to vote in any election." If kids were given the same tests that adults whose brains are atypical must pass in order to vote, then many pre-adolescents would qualify as competent (see also: ableism, neurodiversity, and Suffrage for Americans with disabilities). Additionally, ballots cast by someone (ie kids) with little understanding might simply randomly allocate votes and have no impact on the outcome of the election.

Further, law professor Vivian Hamilton argues that in light of findings from research in developmental psychology and cognitive and social neuroscience, governments can "no longer justify the electoral exclusion of mid-adolescents by claiming that they lack the relevant competencies."

John Wall argues that precisely because children and youth think differently than adults, that they would make unique contributions to decisions around issues with their fresh perspectives and useful abilities such as compassion for suffering and even great wisdom.

As for knowledge around the political decisions at the ballot box, Daniel Hart argues that 16-year-olds have proved just as capable of evaluating the candidates that align with their values and interests as 18 and 19-year-olds (though not as much knowledge as 30 year-olds).

Others dispute whether not having the average political knowledge of an 18 year-old is a good reason for exclusion, given the double-standard of how adults don't have to prove some level of political knowledge before voting. Additionally, not every voter is expected to know about every issue, but the wisdom of the crowd from different expertise and life experiences is what contributes to a healthy and informed citizenry, including perspectives that are unique to those under 18. Most people use heuristics (political party, endorsements, etc.) to decide who to vote for, there's evidence that heuristics can be a more effective approach in voting rationally than a detailed issue-by-issue analysis of each candidate in each race. Additionally, while prior knowledge and experience can provide greater understanding, it can also lead to less informed decision-making by closing an otherwise open mind.