The focus of this study was on developmental reserve capacity in old age as revealed by testing-the-limits. Examined were (1) the time course of training-related magnification of age differences in serial word recall and (2) predictability of training gains by pretest individual differences in cognitive abilities. In 20 sessions, young (n=18) and old (n=19) adults were taught to recall lists of 30 words using the Method of Loci. Age differences were magnified early in practice at long presentation times (20 sec and 15 sec per word) and later at 5 sec per word. Regression of posttraining scores on various pretraining abilities revealed significant effects of digit symbol substitution. Also, consistent with the assumption of age-related decline in developmental reserve capacity, the unique variance in serial word recall associated with age group became more salient as the training unfolded. (PsycINFO Database Record (c) 2007 APA, all rights reserved)