Working memory updating (WMU)---the ability to maintain accurate representations of information changing over time---has been successfully used in individual differences research to predict higher cognitive abilities. For instance, WMU has been found to predict fluid intelligence and reading comprehension. However, little is known about the underlying component processes of WMU or the relationship between WMU and working memory capacity (WMC). A decomposition of WMU into three distinct components---retrieval, transformation, and substitution---was implemented into a standard WMU paradigm. Experimental conditions featured every possible combination of these components. The decomposition was used to analyze the relationship between WMU subcomponents and WMC. We utilized structural equation modeling in a novel way, in that both interindividual variability and experimental effects on mean performance measures (RT and accuracy) were accounted for concurrently. Results suggest that the proposed components make distinct and additive contributions to WMU. We found that WMC reliably predicts WMU in general, but also that some components of WMU are independent of WMC. Hence, WMU and WMC may make independent contributions in predicting higher mental abilities.