International large-scale assessments (ILSAs) play a distinct role in the United States' decentralized federal education system. Separate from national and state assessments, they offer an external, objective measure for the United States to assess student performance comparatively with other countries and over time. The US engagement in ILSAs derives from both a legal mandate and a history of international collaboration among governments and among researchers. From a US perspective, ILSAs function primarily for benchmarking and related purposes. The assessments in which the United States participates vary in terms of their focus, countries participating, subject-matter coverage, cycles and samples. Each offers unique measures on how well US students are performing relative to their counterparts internationally. The ILSAs serve as a small but significant complement to the US federal government's investment in its national assessments. Current federal support for state benchmarking to international assessments brings an added dimension to the portfolio of US participation. Additional efforts could also expand the usage of ILSAs and their potential impact.