Dielectric capacitors including dielectric compositions with high dielectric constant, low dielectric loss, and high thermal stability are disclosed. The dielectric compositions can include a dipolar polymer having a high glass transition temperature (e.g., Tg>150° C.) in combination with either (i) another dipolar polymer having a high glass transition temperature (e.g., Tg≥150° C.) in the form of a blend, or (ii) the dipolar polymer with an inorganic interfacial agent volume content less than 2 vol % in the dielectric composition.