A new interpretation of mathematical formulas developed by Keyfitz illustrates how the concept of entropy (H) can be applied to the analysis of marriage dissolution. The quantities H(divorce) and H(widowhood) indicate the changes in marriage duration which would result from small, constant changes in duration-specific divorce and widowhood rates, respectively. An examination of values for the United States, Nepal and Colombia illustrates the utility of H(i) in assessing the impact of changes in widowhood and divorce and clarifies the relationship between H and changes in life expectancy.