This manuscript describes the results of the first round-robin test (RRT) of the American Association of State Highway and Transportation Officials TP 144-23 (Turner-Fairbank Highway Research Center Alkali-Silica Reaction Susceptibility Test [T-FAST]). The RRT participants analyzed six samples in the forms of four coarse and two fine aggregates of varying alkali―silica susceptibility. Fifteen datasets were received and screened based on quality and statistical criteria. The single-operator and multilaboratory coefficients of variation (CVs) were calculated based on the six datasets that passed the initial screening phase. The results showed significant variability in the multilaboratory CVs. Different aspects of T-FAST and the analytical method were identified as the main sources of variability. Despite the significant CV, the elemental concentration results and the T-FAST classification the participants reported captured the alkali-silica susceptibility of all the samples.