The number of people added to the human race every year is equal to the population of Mexico, and the overwhelming majority of them are born in conditions of growing poverty. In forty years the world's population has doubled, and experts predict it will nearly double again in the next fifty. Meeting the needs of so many people will require a five- to tenfold increase in economic activity, and doubts are growing that the earth can sustain this. Churches, like the human family as a whole, are deeply divided over what to do about it. The author makes a lucid survey of the various "perils" of the population question, and gives an overview of responses already being made by churches and the ecumenical family.