Central to most religions is the practice of prayer, and many individuals use prayer spontaneously to cope with their problems (McCaffrey et al ., 2004 ). But because prayer 'has been largely marginalised by social scientists who study religion' (Dein and Littlewood, 2008 , p. 39), virtually nothing is known about prayer and close relationships. This chapter describes a research programme on prayer and close relationships, explores the implications of such work, and, in doing so, attempts to fill this gap. 2 First, however, it is important to briefly analyse the construct of prayer.Prayer conceptualised Prayer has many potential referents. William James ( 1902 , p. 464), a founding father of modern psychology, defined prayer as 'every kind of inward communion or conversation with the power recognised as divine . . .'. And it has further been argued that 'if prayer is regarded as every kind of communication with the power recognised (by the pray-er) as divine, then, arguably, all individuals pray to some degree' (Breslin and Lewis, 2008 , p. 10). Many types of prayer exist. For example, Poloma and Gallup ' s ( 1991 ) taxonomy identifies ritual prayer, petitionary prayer, colloquial prayer and meditative prayer. Given such distinctions, researchers need to be clear when describing the effects of prayer because the impact of ritual or meditative prayer could be quite different from that of petitionary or colloquial prayer.In the research discussed in this chapter, the focus is on colloquial, petitionary prayer, a form of prayer that invokes the deity ' s help in response to specific needs, using the individual ' s own language rather than a set or memorised prayer. Attention is focused on this form of prayer because it may be used in response to ongoing stressors and life events, and because of its ability to serve as a point of connection with family members, but this should not be taken to imply that other forms of prayer (e.g. meditative or ritual) are a less valuable focus of future research attention or that other forms of religious and spiritual activity should be ignored.