Twelfth-grade students in 42 secondary schools took the Tests of Developed Ability in the Spring of 1956. The students also supplied information about their background, experiences, interests, and estimations of their own ability. Their teachers provided school grades and nominations of students with outstanding ability in the fields covered by the tests. The resulting mass of data were explored by making tabulations of all variables against test scores, with breakdowns by sex and general ability level. It was found that the TDA science tests successfully reflect scientific interest and experiences. They are related to course work in physics, chemistry, and mathematics, less so to courses in biology. Reading in science is very much related to test scores. While SAT-M relates most closely to the strictly mathematics variables, neither SAT-V nor SAT-M approach the relationship of the science TDA's to the science rating and experience variables. Social Studies Abilities, practically an alternate form of the Social Studies Achievement Test, is excessively sensitive to verbal comprehension and, consequently, reflects humanities rather than social studies experiences. Its relationship to writing hobbies, general reading, and language courses greatly overshadows some appropriate correlation with the reading of history and government. Courses other than American History are not related to the test scores. In general, the humanities tests successfully reflect interests and experiences in their area. While these relationships indicate that the humanities tests measure appropriate characteristics of the student, it should be noted that SAT-V has substantially the same relationship.