There are many different techniques used with agile software development methods. Some of these, such as common coding guidelines and test driven development, are widely adopted and there appears to be a consensus that they can be beneficial. Others, however, are more controversial, none more so perhaps than pair programming. This technique meets resistance both from developers, who do not always wish to program with another person, and from managers, who see the sharing of a workstation as a potential barrier to programmer productivity. Its supporters, however, claim that it can have many benefits, in particular improving software quality. In this paper we look at the outcomes of previous research into the effects of pair programming and analyse some survey data to see how practitioners perceive its potential benefits for project outcomes in terms of quality, productivity, stakeholder satisfaction and cost. We conclude that the survey data appears to reinforce many of the previous claims made for the benefits of pair programming, but also raises questions that need further investigation.