Non-violent communication is a book written by Marshall Rosenberg. I've never read it, but from my skimming, it is similar to the communication practice taught at Community Mediation Maryland. However, there are some key philsophical differences, and I think it's aimed at different goals. I don't know for sure because I haven't read it yet! Generally it is quite popular among mediators.

Possible method of engagement: a one-time book club meeting to discuss this book, with the expectation that everyone in attendance has read it before attending. If desired, I could bring exercises to practice the skills. Noting that I have not read it before, but I do come at it with an expert eye and some familiarity with the broad topic, this would be like a self-guided skills workshop.

Exercises would be like: simulated role play, where you're given some character background and have to act out a conflict. A chance to practice the language. I don't really know for sure yet what it would look like, having not yet read the book.