Developing negation and assertion of children from 1 to 3 ages. In this article is given a value of Freud’s, Behaviorist’s, Bruner’s, Piajet’s and Jelesco’s theory for studying of development assertion and negation of children from 1 to 3 ages, it has been shown the new method of studying .Basically on this method it had been worked out and put into practice the method of certifying experiment of learning assertion and negation. These facts are testified that in this age the children in solving thinking operation more often can say «yes» (assertion), than say «no» (negation). In our opinion it’s explained that educators always use traditional assertion forms in learning and education children from 1 to 3 ages.