Glass compositions and glass fibers having low dielectric constants and low dissipation factors that may be suitable for use in electronic applications and articles are disclosed. The glass fibers and compositions of the present invention may include between 45.0 to 58.0 weight percent SiO2; greater than 18.0 weight percent B2O3 and no more than 26.0 weight percent B2O3; greater than 16.0 weight percent Al2O3 and no more than 23.0 weight percent Al2O3; between 0.25 to 12.0 weight percent P2O5; greater than 0.25 weight percent CaO and less than 5.00 weight percent CaO; less than 4.50 weight percent MgO; greater than 0.25 weight percent CaO+MgO and less than 5.00 weight percent CaO+MgO; less than 0.80 weight percent Fe2O3; and less than 0.50 weight percent TiO2. Further, the glass composition has a glass viscosity of 1000 poise at a temperature greater than 1350 degrees Celsius.