Focus Group Discussion
Evaluation method: gathering qualitative data
A very nice method to gather qualitative data in an evaluation including "field work" is the Focus Group Discussion. It can give insights into the why of more quantitative data. Additionally, as it is a qualitative interview with a group of people, it can also give you more insight into group dynamics.
The SocialCops Blog gives a very nice explanation of the when and howto of a Focus Group Discussion: http://blog.socialcops.com/resources/conduct-successful-focus-group-discussion