Maturity operates in Much Ado About Nothing as a marker of age and veneration, but also of personal growth. The young characters – Claudio, Benedick, Beatrice, and Hero – are all immature in matters of love, because they have yet to figure out how to deal with it in a way that doesn’t compromise them. The older characters, like Leonato and Don Pedro, have the respect that comes with age – they’re wiser in the ways of the world – but they lose out because of their age too. When Claudio refuses to fight Leonato and Antonio, he says it’s because they’re old men without teeth.
Maturity is the trait most lacking in all of the play’s characters; their susceptibility to pride and deception, and their inability to think before drawing their conclusions, are more about immaturity than any other quality.
Benedick and Beatrice are immature throughout the play. In the final scene, where they nearly fail to admit their love for each other, they prove that they have not matured at all throughout the course of the play.