Research frameworks to learn about the causes of happiness or unhappiness are of three broad kinds, based primarily on the environment, the person, or combinations of those two. It is clear that an approach that joins environments and people (the third option) is needed for a complete understanding, but a first step is to characterize the features of each contributing domain and to identify their modes of operation. Much research in this field has therefore been either primarily environment-centered or primarily person-centered. An emphasis of one or the other kind does not necessarily deny the need for a joint account, but a more focused approach can be methodologically more appropriate at this stage of understanding. Environmental inputs to happiness are explored in this and the following four chapters, chapters 9 to 11 emphasize person-centered issues, and research into both influences simultaneously is examined in chapters 12 and 13.