During the development of large-scale school achievement tests, panels of independent subject-matter experts use systematic judgmental methods to rate the correspondence between a given test's items and performance objective statements. The individual experts' ratings may then be used to compute summary indices to quantify the match between a given test and its target item domain. The magnitude of alignment index variability across experts within a panel, and randomly-sampled panels, is largely unknown, however. Using rater-by-item data from alignment reviews of 14 US states' achievement tests, we examine observed distributions and estimate standard errors for three alignment indices developed by Webb. Our results suggest that alignment decisions based on the recommended criterion for the balance-of-representation index may often be uncertain, and that the criterion for the depth-of-knowledge consistency index should perhaps be reconsidered. We also examine current recommendations about the number of expert panelists required to compute these alignment indices.