The psychology of a difficult child* presents a most crucial problem for investigation from various angles, because the notions of "difficult child" and "hard-to-raise child" are very broad, Here, in fact, we confront categories of children who differ greatly from one another, who are united by one negative attribute: they all present difficulties in terms of upbringing. Therefore, the terms "difficult child" or "hard to raise child" are not scientific terms and do not represent any definite psychological or pedagogical content. It is a general label for huge groups of children who differ from one another; it is a prefatory term, advanced out of practical convenience.