My teacher gave me stacks and stacks of notes on thematic concerns in relation to The Crucible, but i cant be bothered looking them up yet and typing out notes. SO...i did a quick google search and got this..
"In the community you can see many factions develop, which individuals belong to or are excluded from. Some characters, like John Proctor, choose not to belong for the sake of preserving their own values rather than being caught up in the hysteria sweeping the town. There is the notion of the "outsider" in Tituba as well as some other characters."
So from that, it sort of gives you a starting point. There are also some different aspects of belonging, they include:
-inclusion
-exclusion
-barriers to belonging (such as age, the young girls didnt really have no status)
-choices to or not to belong
-attitudes to belonging
-identity and belonging of the self
There are a few other themes for The Crucible as well, but most of them can be related back to the main theme of 'belonging' anyway. See if you can go and track down some study guide books for the crucible at a library or something, cause i know there are some ok ones out there, such as the 'Get Smart' guides.