This paper presents a review of our studies of interfaces in liquid-phase sintered materials. Recent studies of three different types of interface are discussed, namely, (i) the interface between the free surface of the crystal and the glass, (ii) the interface between the intergranular glass and the crystal and (iii) the interface between the crystallized glass and the substrate crystal. Model systems with relatively well known thermodynamic and crystallographic properties have been chosen. The relationship between the three types of interface is discussed. The dewetting of silicate liquids on free surfaces provides an opportunity to study directly the interface between the free surface and glass. Observations on polycrystalline samples and bicrystals give new understanding of the interplay between intergranular glass layers and the adjoining crystalline grains. Crystallization of the glass on single-crystal substrates directly gives information about the crystallized-glass/crystal interface.