This test will be very useful to employers seeking high-grade clerical service and probably in selecting administrative or supervisory officers. In the public schools it will be useful in some instances in classifying pupils for instruction. As a diversion in the home or social group it will have slight value. _Directions for Giving the Test._ This test has ordinarily been given as a test of several individuals at the same time. It is probable that it will not be as useful when given to one individual at a time as when used as a group test. The instructions are given here, however, as with the remainder of the tests for non-English-speaking persons, with the needs of examining foreigners individually uppermost in mind. By reproducing on the blackboard or on a wall chart the introductory examples one may adapt with almost no change the method of administration here described so that it will work equally well with a group. It is advisable to prepare such introductory charts and to give the tests as group tests rather than as individual tests, not only with the Digit-Symbol Substitution test but also with the other Mentimeters numbered from 2 to 10. [Illustration: Key: This shows the mark for each number] [Illustration: Make under each number the mark which should be there] [Illustration: Key: This shows the mark for each number] [Illustration: Make under each number the mark which should be there] The individual to be tested should be shown the page on which he is to work, for not more than twenty seconds, and should then be shown the two examples appearing on the title page under the printed instructions, “Make under each number the mark which should be there.” The examiner should then compare his key and the digits appearing in the sample series and should write in the proper spaces the appropriate symbols. The idea of getting the symbol from a key will be emphasized and made clear if the examiner at each point moves his finger or pencil from the digit in the example to the digit in the key, then to the symbol in the key and back to the empty space beneath the digit in the example. When all the spaces of the example have been filled (this should be done very slowly at first and then more rapidly toward the end of the example), the examiner should open the booklet, supply a pencil, and say, “Now! Go ahead! Put them in! Hurry up!” Exactly two and one half minutes (150 seconds) should be allowed from the time the examiner says, “Go ahead,” to the time he calls, “Stop!” All papers should be closed immediately and handed to the examiner. _Directions for Scoring the Test._