An attempt is made to reveal the essence of the method of testing through analysis of three groups of features: 1) necessary in relation to the method though not specific to it; 2) necessary and specific but only in relation to particular types of testing procedures (type-constituting); 3) necessary and specific to the method as a whole. The last group includes two features: a) presence in the structure of every testing procedure of a specially elaborated mathematical-statistical apparatus for procession of corresponding data and for estimation of the quality of the test itself, b) wide, repeated application of every procedure. The analysis has shown that testing is one of the best developed and productive methods in the psychology's arsenal possessing besides that a high potential for further development.