This text deals with a theme that accompanies us throughout the years and that even old it remains current, due not only to the innumerable debates that day by day surround it as due to the diverse proposals of Constitutional Amendments that seek an alteration in the legislative system in force. The criminal majority is a very controversial subject, therefore, of a side, are the defenders of its maintenance, alleging the impossibility of the alteration for being a clause stony; of another one, are those that require its modification sustaining that the current penalties are very soft. The present book, besides a historical evolution on the theme, shows how the age of criminal responsibility has evolved. In this way, a comparison was made with the legislation of other countries. In the sequence, the favorable and unfavorable aspects of an eventual reduction of the age of criminal responsibility were pointed out, to, at the end, to treat about the stony clause, that turns the current regulation, insusceptible of any alteration.