I used to work for UPS. I was a seasonal worker, and thus was employed for about 2 months or so. Nobody talked to me about the union, because they didn't consider seasonal workers to be union candidates. I was wondering, though: If I wanted to work for UPS again, on a non-temporary basis, must I join the union? According to this thread, which is two years old: http://www.browncafe.com/community/threads/does-ups-make-you-join-the-union.205600/ Most people in this thread said you must join. The driver I worked with also believed you must join. I think the man who hired me also said permanent workers had to join, though I don't remember exactly. At the time, I thought this was legal. However, I've been reading that it's illegal to be forced to join a union. That is, union membership cannot be compulsory. In Colorado, I think I could be forced to pay some union dues. Is this the case? Here's what I was reading: http://www.nrtw.org/a/a_1_p.htm My second question is simple: If you work for UPS, and don't join the union, how would the company treat you differently?