This chapter considers how happiness or unhappiness can affect behavior, in contrast to the emphasis in previous chapters on possible causes. The state of happiness is clearly desirable at a personal level, but it might also be important because of implications that are themselves valued. For example, it could be that happy people are more likely than unhappy ones to behave effectively in organizations. Research has suggested that such a causal process can occur, but that other directions of influence (from behavior to happiness, for instance) may also be important in some cases. As in earlier chapters, the presentation emphasizes findings from employment settings, but nonoccupational investigations are also considered.