Building on promising pilot research, this application outlines a research program to document 'hard' outcomes (e.g., observed rather than self reported behavior, bio markers) of colloquial, petitionary prayer (CPP) for a partner. In doing so, it opens up a new area of research on the impact of CPP prayer on physical, as well as, relationship health. It uses a variety of methods including behavioral observation, and physiological measures (blood pressure, hormone assays) in the context of experimental and longitudinal research designs that examine a variety of close relationships (romantic, marital and friendship relationships). Six studies are proposed to test seven major hypotheses. For example, one study investigates whether CPP for a spouse prior to an acute stressor (marital conflict) leads to smaller increases in cortisol and less cardiovascular reactivity relative to spouses who do not pray. Outputs will include twelve presentations at national and international scientific meetings and publication of manuscripts in prestigious peer reviewed journals (the pilot research appeared in such journals) and at least three book chapters. It is also anticipated that the research will attract media attention (pilot research resulted in an article in the Economist) resulting in several mass media stories. With a foothold established in mainstream, prestigious journals, it is time to consolidate on this progress and make an enduring impact by providing 'hard' evidence (prior work is limited to self report) that even the most skeptical scientist will find hard to refute. The new proposed frontier, physical health, has the potential to find evidence supportive of Sir John's prediction that 'if governments encourage people to become more spiritual there will be a reduction in healthcare.'