Qualitative research consists of methods that allow for a more in-depth understanding of phenomena and encompasses techniques such as focus groups, in-depth interviews, and participant observation. The guidelines that pertain to sampling and analysis are different from those which govern quantitative techniques, but they can be applied just as rigorously to ensure the validity of the results. This article introduces these methods and criteria and illustrates how qualitative and quantitative methods can be combined in order to improve what is learned from each.