Normal adult aging is known to be associated with lower performance on tasks assessing the short-term storage of information. However, whether or not there are additional age-related deficits associated with concurrent storage and processing demands within working memory remains unclear. Methodological differences across studies are considered critical factors responsible for the variability in the magnitude of the reported age effects. Here we synthesized comparisons of younger and older adults' performance on tasks measuring storage alone against those combining storage with concurrent processing of information. We also considered the influence of task-related moderator variables. Meta-analysis of effect sizes revealed a small but disproportionate effect of processing on older adults' memory performance. Moderator analysis indicated that equating single task storage performance across age groups (titration) and the nature of the stimulus material were important determinants of memory accuracy. Titration of storage task difficulty was found to lead to smaller, and nonsignificant, age-differences in dual task costs. These results were corroborated by supplementary Brinley and state-trace analyses. We discuss these findings in relation to the extant literature and current working memory theory as well as possibilities for future research to address the residual heterogeneity in effect sizes. (PsycINFO Database Record (c) 2019 APA, all rights reserved).