It depends on what your government is willing to do to maintain population. For instance, if you don't care what the people think / government has absolute power, you could simply kill off people when you're above your cap. However, I get the feeling that this approach isn't what you're going for, so I'll provide a couple other options.
Educating people about the dangers of unprotected sex and providing contraceptives is a very good way of reducing unwanted pregnancies, allowing all children born to have been planned for. While not significantly reducing the danger of overpopulation, this policy makes population growth/decline/stagnation more predictable and manageable by your government.
Shalvenay touched on this, but advanced societies tend to have lower birthrates, mainly as children have stopped being necessities (for subsistence farming) and have become something more of a burden on parents. After all, it used to be that children helped produce food and clothes, but now parents have to provide that for them. Children are also an enormous time commitment, so for the most part only people who want children, knowing fully their responsibilities, have children. To increase this effect in your society, your government could sponsor efforts to develop underdeveloped parts of the world, if any exist. Once your planet is sufficiently developed, you could maximize the time commitment of children by making daycares illegal, possibly under the premise of helping children by having their parents be the ones who raise them.
Even with both of these options in place, your population will still grow. Just look at the US, one of the most developed countries in the world, where the birthrate is still significantly higher than the death rate. Unless every person in society is willing to limit the number of children they have, you're going to need to take extra steps. If you want to truly and reliably stagnate populations, your government is probably going to have to become morally questionable.
You could develop medicine that babies are given at birth to render them infertile, and only with a government permit could they be provided with a drug to stimulate their reproductive systems again. The downside of this approach would be the immense resources required to manage these permits and the possibility of wealth becoming a factor in securing one.
Brave New World-esque factories
If you've ever read Brave New World, you'll be familiar with this suggestion. If your society is advanced enough, you could produce children in artificial wombs, making entire factories for children. This would give the government complete control on population growth with comparatively fewer resources.
If you use any of these options, your government is going to need to do a couple things to ensure their success. Firstly, census taking will have to change. Reliable death counts and birth rates will need to be calculated more than every ten years, probably at least yearly. Computerized birth and death certificates that automatically add to a counter is one option that comes to mind. Secondly, the government will have to take complete control of the world, if they haven't already. People cannot be allowed to have the freedom to have children if you seek to manually curb population growth. However, there is one final option your wise government can take if it does not wish to pursue the above methods.
If your government remains in power forever, it is safe to say that if they wait long enough, the population will grow faster and faster, until food cannot be produced fast enough. This will cause mass starvation and the population will drop significantly and then grow to a sustainable level. Unfortunately, on Earth a "sustainable level" will mean that nearly every aspect of the environment becomes artificially controlled to produce just barely enough food for the now stagnant population. Foods that are efficient to farm/grow like corn, potatoes, and fish will begin to dominate markets, and many species useless to humans will die out.