A study was designed to examine relationships of aptitude level to training performance on tasks of varying complexity and to determine if differential job training might be required. A complexity rated training battery with eight tasks (simple/choice monitoring, rifle assembly/disassembly, equipment preparation, map symbols, phonetic alphabet, and position plotting) was administered to 183 recruits selected through Armed Forces Qualification Test (AFQT) scores. Three homogeneous experimental groups were formed from subjects with different aptitude levels (HI-AFQT, MD-AFQT, and LO-AFQT). Results on simple and choice monitoring tasks revealed LO-AFQT subjects displayed poorer response times compared to HI-AFQT subjects. Rifle assembly/disassembly task differences were noted in favor of HI-AFQT subjects for mean response time and prompts. LO-AFQT subjects required more prompts, trials, and learning time than HI-AFQT subjects on the equipment preparation task. Wider within-group variability was noted for LO-AFQT subjects than other groups on map symbols and phonetic alphabet tasks. On the position plotting task LO-AFQT subjects required more training and displayed more within-group variability than HI-AFQT subjects. Findings suggest efficient training will depend on recognition of individual aptitude differences and instructional program designs compatible with individual learning rates and final performance capabilities. (CSS)