Attempts to modify or ameliorate the effects of declining cognitive abilities of the elderly have met with limited success. To focus on the effects of age in cognitive processing capacity (CPC), Furukawa's (1977) CPC test was administered individually to 3 age groups (16-30, 31-45, and 45-60) of 15 subjects each. Speed of processing old and new verbal knowledge and old quantitative knowledge was also examined. Analyses of results revealed that the oldest subjects: (1) had the lowest mean CPC; (2) experienced the most difficulty with verbal knowledge but surpassed younger subjects with quantitative knowledge; and (3) were not affected by proactive interference across four learning lists. Middle-aged subjects surpassed both younger and older subjects in processing antonyms and showed a possible proactive interference effect. The youngest subjects excelled in retrieval of synonyms and in the acquisition of new knowledge. Overall, the strongest correlations between CPC and performance existed in processing new knowledge. (Author/JAC)