Written test, GD and Interview were the three basic steps. In the first round, written test and GD were conducted. Once the people were shortlisted from this process. they were called in for an interview with the Executive Director in New Delhi. Note that this process is only for experienced hires.
The interview in Delhi was short and easy going. They basically wanted to understand your passion for working with rural communities. Once they are satisfied with that, rest all is easy.