The world as a whole, and to a lesser extent this country, is confronted with the strong possibility of an unprecedented increase in its population. Pressure of population will produce tensions which will pose problems to psychiatrists. But other social events will give rise to generally similar tensions which will thus have multiple causes. It will then be difficult to separate the effects of population pressure from the effects of other causes and there may be illjustified swings of opinion such as we have seen in the past.