This article reports the impact of one critical process parameter, the heating rate during sintering from 530 to 850 degrees C, on the densification of a crystallized low temperature co-fired ceramics (LTCC). At a low heating rate the densification of LTCC is impeded by the competing crystallization processes, resulting in less shrinkage, lower density and consequently lower dielectric constant. Microstructural evidence is provided to analyze the multiple crystalline phases formed during sintering process. It is concluded that an optimized sintering profile should have a heating rate that allows full densification prior to onset of crystallization, follow by a full crystallization to limit the amount of residual glass for enhanced dielectric properties.