Two courses on logic gates were administered to 1,191 male and female recruits in Basic Military Training in 3 studies (448, 431, and 312 subjects, respectively) to evaluate the relative validities of the Armed Services Vocational Aptitude Battery (ASVAB) and the Learning Abilities Measurement Program (LAMP) tests in predicting individual differences in the acquisition of declarative knowledge (measured by the accuracy in solving problems) and the development of procedural skill (measured by the time required to solve problems). In general, the LAMP tests added about 20 percent unique valid variance to the ASVAB tests in predicting these criteria. Furthermore, for both criteria, the LAMP test alone accounted for more variance than did the ASVAB tests alone. Analyses indicate that the advantage of the LAMP tests was neither due to concurrency effects, nor obtained at the expense of excessive testing time. Although LAMP tests and the criterion tests used common methods, arguments are presented contending that most of the covariance associated with common methods was meaningful to the task being learned and performed. Thirty tables in the text and six more in two appendixes present study findings. (Contains 22 references.) (Author/SLD)