The interesting thing about population is that its rate of growth (excluding immigration) falls as societies become more developed. The best way to achieve a stable, or even falling, population, is to promote development in currently underdeveloped countries. I'll probably get a [citation needed] comment at this point, but the data is out there.
No need for Malthusian doom and gloom. Development will solve the "population problem".
The problem is the environmental impact of our current path of development. A steady move to a more environmentally sustainable development model, combined with a development push will (well, "may" is a probably a better word) lead to a better, more viable, planet for all.