The views expressed in this Working Paper are those of the author(s) and do not necessarily represent those of the IMF or IMF policy. Working Papers describe research in progress by the author(s) and are published to elicit comments and to further debate. The paper develops a general equilibrium framework to examine the economic implications of population aging in Japan. Particular attention is paid to aggregate saving behavior which is modeled on the basis of empirical age-earnings profiles using a life-cycle approach. The paper's objectives are to (i) estimate the output loss caused by demographic changes and assess the impact of aging on Japan's government finances; and (ii) compare fiscal policy options with respect to their effects on output growth and economic welfare.