Dyadic latent panel analysis (DLPA) was applied to eight waves of the Panel Study of Belgium Households (N = 954 couples). DLPA decomposes the observed variance of both members of a dyad into variance due to stable factors, factors that gradually change over time, and occasion-specific factors including random error. Total observed similarity between members of a dyad on one occasion is decomposed into stable similarity, similarity in factors that change over time, and occasion-specific similarity. The results show that depressive symptoms are influenced by stable and changing factors and that spousal similarity in both factors contribute to spousal similarity in depression on a single occasion. Spousal similarity in factors that change gradually over time suggests that shared-environmental factors contribute to depressive symptoms.