In recent years, several jurisdictions have lowered the voting age, with many more discussing it. Sceptics question whether young people are ready to vote, while supporters argue that allowing them to vote would increase their specific engagement with politics. To test the latter argument, we use a series of register-based surveys of over 10,000 German adolescents. Knowing the exact birthdates of our respondents, we estimate the causal effect of eligibility on their information-seeking behaviour in a regression discontinuity design. While eligible and non-eligible respondents do not differ in their fundamental political dispositions, those allowed to vote are more likely to discuss politics with their family and friends and to use a voting advice application. This effect appears to be stronger for voting age 16 than for 18. The right to vote changes behaviour. Therefore, we cannot conclude from the behaviour of ineligible citizens that they are unfit to vote.