The vibrant debate on randomized experiments within international development has been slow to accept a role for qualitative methods within research designs. Whilst there are examples of how 'field visits' or descriptive analyses of context can play a complementary, but secondary, role to quantitative methods, little attention has been paid to the possibility of randomized experiments that allow a primary role to qualitative methods. This paper assesses whether a range of qualitative methods compromise the internal and external validity criteria of randomized experiments. It suggests that life history interviews have advantages over other qualitative methods, and offers one alternative to the conventional survey tool.