What explains the difference in the financial market constraints faced by developed versus developing (or emerging market) nations? In my previous analysis of the influences of the government bond market on national policy making, I posit that, because of professional investors' incentives and information needs, financial market pressure will vary across groups of countries. In the advanced capitalist democracies, market participant consider key macroeconomic indicators, but not supply-side or micro-level policies. The result is a "strong but narrow" financial market constraint. Government that conform to capital market pressures in select macroeconomic areas, such as overall governments budget deficits and rates of inflation, are relatively unconstrained in supply-side and microeconomic policy areas. For the most important developed nations, the constraint may not be very strong: the archetypal current case is the continued ability of the United States government to borrow at relatively low rates of interest, despite its large and growing budget deficits.