L.S. Vygotsky laid the foundation for the uniting of different directi
ons in the studies of developmental anomalies into special psychology
as a branch of psychological science. These foundations are: special f
eatures of mental activity characteristic for different types of devel
opmental anomalies; marking out of study objects and working out of sp
ecial methods of examination. L.S. Vygotsky's ideas make possible the
realization of a new approach to differentiated psychological diagnost
ics of developmental anomalies.