I have a master's in chemistry. I doubt that I will go back, as I am too used to getting paid reasonably well and not having to work weekends very often. I am 29, which would mean that even if I started today I would not have a phd plus the expected postdoc before I hit 35. And I could forget having the chance at a husband or family because I wouldn't have the time for that. Unfortunately, a master's degree doesn't count for sh*t in my field if you are planning to go back to school. You have to start from the beginning again. I originally planned to stay for the phd, but ran into some bad luck with the advisor. They basically control your life (well, at least if you graduate and with what degree) and can make it a living hell if they choose to. I don't mean to rant, but maybe this would help some naive younger person.