The distribution of family income among seniors in Canada has changed substantially over the past decade, reflecting an overall increase in family income and an increase in income inequality.  In this study, I use semi-parametric decomposition methods (developed by Dinardo, Fortin and Lemieux, 1996) to determine the extent to which various factors have contributed to this shift in the income distribution.  I focus on disentangling the effects of recent increases in elderly labour market activity and the effect of changes in women's experiences in the labour force over the past four decades as this now translates into greater access to pensions and other retirement income independent of their marital status.  Using Canadian data from the Survey of Labour and Income Dynamics, I find that increases in employment among elderly men and women can account for approximately 30% of the change in equivalent after-tax family income inequality among seniors.  Most notable, the results suggest inequality among senior families would be 20% less in 2005 if women's access to pensions had remained at its lower rates from 1996.  Other important factors that help explain the changes in income inequality include changes in  women's education and past experience in the labour force, men's education levels, access to public pensions, and assortative mating in the marriage market.