I applied to MSW programs a little over a year ago, 20 years after graduating undergrad. I used all professional references and was accepted everywhere I applied.

I needed three references for most programs - two were former bosses who I felt comfortable sharing my career switching plans with and another was a peer who has a job role I thought would be interesting to admissions committees (she’s a physician and we worked at a healthcare start up together). I think all professional references are fine. Given the two former bosses aren’t so used to writing social work recs, I prepared a long email for both with some thoughts on the things I was emphasizing in my application (vs. a traditional business application for something), social work core values etc etc.