We have investigated the ternary glass AgI–Ag2S–AgPO3, where the ratio of AgI:Ag2S is 1:1. As the amount of the dopant salts increases, the glass transition temperature decreases, and the conductivity increases to about at room temperature for an 88% mol fraction of AgI+Ag2S. The structure factor, S(Q), shows a prepeak at low Q values (0.6–0.9 Å−1), as observed in AgI–AgPO3 glasses, but not in pure AgPO3 or in Ag2S–AgPO3. The concentration dependence of the prepeak indicates medium range atomic correlations growing in concentration and size.