Methods to join the metallic interconnect and ceramic electrolyte in planar, solid oxide fuel cells (SOFCs) will be described and briefly assessed. A particular focus will be on strategies to overcome thermally induced residual stresses that limit the stack structural reliability. Two principal strategies are increased seal compliance through seal geometry or material property changes, and matching of thermal expansion coefficients through the use of metal and ceramic fillers. The associated challenges of each are reviewed. The second half of the presentation will concentrate on seal strength testing techniques and their utility in providing scientific information on the seal microstructure and chemistry that ultimately relates to lifetime prediction and performance. Some specific examples with silicate and silicon carbide seal materials will be provided.