Do I Have to Put My SS# on Applications?

Dear Experts, Do I have to put my SS# down on an application if it is requested? I don't like giving out that information, but am worried leaving it off keeps me from getting the interview. What do you think? Our Twitter Advice Project (T.A.P.) is no longer an active campaign. To find an answer to the above question, please use the "Search" box in the right-hand column of this website.