My understanding of desensitization instead of flooding is that you take things slowly and build up towards being desensitized. Like if your phobia is other people; you might start initially with looking at pictures of other people in a book and noting how you feel. Becoming aware of your response and practising grounding skills to feel safe. Working on coping and changing your beliefs about why the pictures are scaring you until you get to where you feel safe with it. Then you move on to something a bit "bigger" like looking at people moving around on tv. Repeat the process of noticing how you feel; grounding; looking at and challenging beliefs and reworking them, reminding yourself you are safe etc. Then increase the exposure, moving it up to looking at people in the distance. Repeat the process of noticing, grounding, reviewing and adapting beliefs, all the while moving at a pace where you don't get too overwhelmed but do keep moving forward. Then it might be seeing one person up closer for a short period of time - repeating the rest of the process. Then having that one person stick around for longer - repeating the rest of the process. You might then talk to them for a few minutes - repeat the process. Introduce a second person - repeat the process. Basically you work out with a T what the fear or phobia or situation is that needs desensitizing, and then work out a plan of gradually introducing you more into that situation all the while staying safe and becoming desensitized. In contrast, flooding would be more like throwing you into a room of 100 people and expecting you to stay there and work things out. Desensitizing can take time because you are building up from being terrified to being safe; and sometimes needing to retake steps .... flooding, if used for the wrong thing and by the wrong person can be dangerous; but in some situations is helpful (sounds scary to me though). One of my T's worked with me on desensitizing a phobia and it is helpful