This chapter considers the working memory processes that contribute to the ability to handle tasks and differences that lead to variations in these working memory processes. Two processes are focused on: active maintenance and information updating. They are important processes that other working memory processes are likely to tap into or build on. Computational models and behavioral studies are described to test the mechanisms subserving active maintenance and information updating. The overaching theory of working memory focuses on the computational mechanisms underlying the active maintenance and updating of information. Simulations made demonstrate computational trade-offs in active maintenance. They provide a strong computational foundation for our overall theory of working memory function. The main theme emphasized is that the grounding of constructs in neural mechanisms can provide important constraints on interpretations of behavioral findings of individual variability.