Barium zinc borosilicate glasses with a molar composition xBaO-(60−x)ZnO-30B2O3-10SiO2, where x ranged from 0 to 60 mol%, were prepared using melt-quenching method. The effect of BaO substitution for ZnO on the sintering, crystallization, and dielectric characteristics has been investigated. The behavior of the studied barium zinc borosilicate glasses was mainly determined by the relative amount of the structural modifier oxides (BaO and ZnO) and the ionic size, and field strength of the modifying cations (Ba2+, Zn2+). Increased amounts of BaO decreased both glass transition temperature and crystallization temperature, while increasing the relative dielectric constant. Sintering occurred before crystallization for glasses where substitution of BaO for ZnO was up to 30 mol%, but for higher substitution levels, crystallization occurred during the sintering process hindering densification.