Understanding the development and multiaxial distribution of expansions is of critical importance in the appraisal of structures affected by alkali–silica reaction. Such expansions were monitored for 33 480-mm reinforced concrete cubes in an effort to develop an improved understanding of the expansion mechanisms in reinforced concrete and broaden the database of experimental results available from which to build tools to aid in the performance assessment of affected structures. The cubes were fabricated using three different concrete mixtures of varying reactivity and contained uniaxial, biaxial, and triaxial reinforcement layouts with different reinforcement ratio combinations. In all cases, the cubes expanded at greater rates in unreinforced directions than in reinforced directions. Furthermore, the reinforcement ratios did not significantly influence expansion behavior, especially in the cases of uniaxially, equal biaxially, and equal triaxially reinforced specimens. Increasing the number of reinforced directions resulted in reduced volumetric expansion development over time and greater differences between expansions in reinforced and unreinforced directions. Cubes with end-anchored, deformed steel reinforcing bars placed in three layers developed expansions exceeding steel yield strains in all directions. Cubes with bars placed in two layers exhibited differential expansions between locally reinforced concrete regions at the edges of elements and unreinforced core regions. Mixture reactivity and environmental conditioning influenced expansion rates but not trends of the multiaxial distribution of volumetric expansions.