The main characteristic of children's play is its mental aspect--the fact that it is based on thoughts and feelings and not on objective reality. During imaginary play, children go beyond the limits of reality, and toys are tools that help them to do this. Children need character toys--toys that play the role of companion or partner--in the early stages of development of play. Young children (under seven years) are not yet able to establish distance from their playthings and hence identify with dolls and absorb their characteristics. For young children, dolls and soft toys become an "alternative self", and in order to be a "good" psychological tool, they should be open to a child's inner world. "Interactive" toys are quite different from this in that they have an independent life of their own. An observational study of 50 children aged 5 to 5 1/2 showed that although they were intensely interested in an interactive toy, their play was at the level of simple functional play, and that the toy evoked no imaginary involvement and no play storylines, even though the children were clearly capable of these higher levels of play. The Moscow Toy and Game Centre (at the Moscow City University of Psychology and Education) have developed methods for evaluating toys, and the key criteria for evaluation are given here. The first step of evaluation is an "ethical and aesthetic filter" that screens out toys that could be a psychological or pedagogical danger. After this, the central criterion is whether the toy will allow children to project their inner world into it. Other criteria include the balance of detailed and schematised imagery and the tendency of toys (such as interactive toys) to encourage simple manipulation over the development of rich storylines.