Are adult students typical in MSW programs? I'm 36 myself and am thinking of doing an MSW part-time. For that matter, I'm thinking of working part-time once I get the degree, since I would prefer to hold onto my current line of work for the time being for financial reasons.

How common is it for people to find the "calling" to do social work as an adult and to then do the work part-time as a "labor of love" while maintaining (what may be at the time) a "necessary" day job?

My MSW program has people up to about 50 years old. Do not let your age discourage you, and go for it!

I am 49. Got my BSW at 25 and MSW @ 30. I've been supervising sw interns for 16 years and have had 7 interns (of 35) who were at the time older than me or nearly the same age (in their 40s and even 50s.) In most cases these were folks who had been financially successful in business and marriage and who were now pursuing life long dreams of more direct hands on helping. Each of those individuals is prospering in their new found profession. One (at least) has found a way to incorporate what would appear to be a totally unrealated (to sw) past professsion into a therapeutic outlet with his clints.
Two others added MSW to their creditials to broaden their skills and competencies in an existing professional area. (one a nurse, the other a Methodist Minister)
One was a political activist from a wealthy family who had never had to "work" (for money) but had suddenly discovered in her 40's that sometimes shaking trees wasn't enough and that planting them and tending to the crop, might be more effective in the long run. And the MSW provided her the particular tools (or at least the credentials & credibility to be hired) to intervene more effectively. (Now her salary goes to support her political agenda. I tried unsuccessfully to teach her that former field instructors were worthy of such financial support.....)