Population,resources and environment are the basic conditions of a country,and the fundamental factors affecting sustainable social and economic development.Population characteristics,and individual and household behaviors determine the use of resources and environmental protection.In order to achieve the goal of scientific development,it is necessary to take all of the three factors into account.Corresponding to this consideration,the Central Commission of the Chinese Communist Party called for "striving to build resources-saving and environment-friendly society" a few years ago,but why the "pattern of population" was excluded from this call? Given this,the leading party group of the National Population and Family Planning Commission proposed the idea of sustainable and balanced population development,which caught much research attention,and received responses from local family planning workers.How to translate a good idea into a theory,and then into practice deserves further discussion.Hence,this forum,"Why a Population-Balanced Society should be Built," brings together three scholars,Zhai Zhenwu,Li Jianmin,and Mu Guangzong who are specialized in this area,to discuss this issue in a greater detail.They have defined the concept of population-balanced development,explored feasible channels to realize such society,and pointed out the future research direction on this topic.As Professor Li points out,population-balanced development is a long-term,historical process;we should neither be too anxious for quick success,nor do nothing.What is important is not how fast we can go,but whether we are in the right direction,and step forward towards that direction.