Binet used this standard of two years retardation in recommending examination for children 9 years of age or over (3 years below age 6 in the first grade) (_77_, p. 44). He adopted it from Belgium. It is also quite commonly followed in this country. The New Jersey law provides for special classes in any school district where there are ten or more children four or more years behind grade. This probably means behind the theoretical position of age 6 in the first grade, one year worse retarded than we suggest examining. Goddard says in one place that “a child who has been in school regularly and is two or three years behind his grade is so suspicious that it is almost certain that he is feeble-minded” (_116_). But later he is much more conservative and says, “The child who is fourteen years old and cannot pass an examination in fourth grade work is almost surely feeble-minded” (_34_). As judged by Strayer's tables the suggestion that examination is desirable for those two years behind a standard of age 7 in the first grade would tend to bring in for examination about 18% of the school boys in half of the cities of 25,000 population and over. This would not be too severe a burden for courts which would be interested only in that portion of these retardates who were brought into court. This school test may be made of decidedly practical use by those working in juvenile courts where most of the cases are with children over this age. It can be applied in a very simple manner by subtracting 8 from the child's age and only passing without testing those who are in a grade in school higher than the number remaining. For example, if the child is 13 years of age, subtracting 8 gives 5. Now, if the child is in the fifth grade or lower, or entered such a grade at the time he was of this age, one should investigate the question of feeble-mindedness. Unless more than one year of the retardation is explained by the person's absence from school since he was six years of age, he should always be turned over to an expert for examination. This retardation of two years in school attainment below the standard of seven in the first grade may indicate feeble-mindedness if the child has been attending school constantly, although the chances are perhaps 6 to 1 that it does not. It is very desirable that we should have more adequate data on this point. A cautious court, however, would inquire into the mental ability of any child—at least two years retarded in school, _i. e._, any child the number of whose school grade is not higher than the remainder after subtracting 8 from his life-age at the time that he entered his last grade or who is not actually carrying the school work of an advanced grade. This latter caution we must now consider. (c) SCHOOL SUCCESS AS A CHECK ON THE BINET DIAGNOSIS.