Genotype by environment (G x E) interactions for the dietary fiber beta -glucan, one of the deciding factors for the end use of barley (Hordeum vulgare L.) grain, are not well understood. The objectives of this study were (a) to investigate G x E interactions for beta -glucan content of diverse barley genotypes across dryland grain-producing environments in eastern Washington, and (b) to determine the range and stability of beta -glucan content exhibited across precipitation zones. We examined 17 two-row, spring barley varieties and breeding lines across eight locations for beta -glucan, protein, and yield in 2017 and 2018. beta -glucan ranged from 1.81 to 7.18 (%, w/w), with a mean of 4.01 (%, w/w). Genotype x year (Y), G x location (L), L x Y, and G x E (G x L x Y) interactions were found for beta -glucan. Univariate models including the regression model with slope (b(i)) and deviation from regression (Sd2), Wricke's ecovalence stability index (Wi2), and Shukla's stability variance (sigma i2) agreed that there was moderate rank stability amongst genotypes. Data generated through this research will provide a better understanding of which cultivars that farmers can grow in their area will meet industry targets and standards for both food and malt barley.