Many Catholic churches use “Familia,” which is for many people an entry into the Regnum Christi movement. Here’s a story about how the movement sought to drive out the founders of that apostolate, Paul and Libbie Sellors. They wrote the materials before it was adopted by the movement, and sought to retain access to them. A court gave that to them, and they’re promoting it under a new name, Together! But that’s not the end of the story, as that first link will tell you.
I was involved in one Regnum Christi apostolate–without being a member. I became involved in College COMPASS through some students at Rice, was invited to speak to a COMPASS gathering in Europe in 2005, helped coordinate a COMPASS national gathering in Houston, and served for a while on the COMPASS advisory board. I stayed for a few days at the Legionary seminary in Rome, and have visited the Legionary seminary in Cheshire, CT. I found the Legionaries I knew to be open to the criticism I gave (they needed to be more upfront with folks about it being a Regnum Christi apostolate, they should not be pressuring students to “incorporate” into RC until at the end of their college years, they should “go in the front door” when starting on a campus or in a diocese, etc.). But there were a lot of things I found very odd about it–including the segregation of men and women (a week before the Houston conference the COMPASS folks were told by the Legion that they couldn’t have men and women stay in the same hotel–some of the students laughed at that and said, “Well, in Europe they had us stay in different countries!”).