What forms do I need to start a nonprofit unincorporated association in Massachusetts?

You need to get the assistance of an attorney to set up the business properly. When you don't even know the proper starting point, you are not likely to be able to complete this without some assistance--and there are severe consequences for a business that purports to be non-profit and then hasn't complied with the proper filings. An attorney that specializes in establishing businesses, business plans and corporations can make sure that, not only will your initial filings be complete and accurate, but your yearly requirements will also be correct. Good luck.