This experimental study aims to investigate at what age Italian children master the logical concept of double negation, according to which two negatives cancel each other out yielding a positive meaning. Previous acquisitional studies on child languages indicate that children show a cross-linguistic preference for a negative concord interpretation of all multiple negation structures, including those that are double negation. Italian children aged between 3;10–8;2 were tested both in the comprehension and in the production of double negation sentences. The results show that Italian children master the Law of Double Negation by age 7;3. Moreover, the data collected suggest that younger children have already acquired this logical complex but, due to their limited working memory capacity, they have difficulty in its implementation.