Some might define a lay ecclesial movement in the Catholic Church by pointing to examples: Regnum Christi, Opus Dei, Neocatechumenal Way, Cursillo, Focolare, etc. Or they might point to the Directory of International Associations of the Faithful as a list of the big ones. Here’s a problem: of the 5 examples listed at least 1 and maybe 2 aren’t movements: Opus Dei is a personal prelature not a movement, and the Neocatechumenal way argues that they are not a movement. They state: “According to its statutes, the Neocatechumenal Way is not a movement or an association, but an itinerary of Catholic formation.”
First, lay movements fall in the canonical category of associations of the faithful. Even if they involve other canonical structures like religious communities, the overall structure is an association.
Second, they primarily involve lay people (not excluding religious or priests but having them in a minority). Some groups, such as the Sisters of Mary, Mother of the Church start as associations with all the other characteristics but have the formation of a religious community as the goal.
Third, they are united around some particular charism, a particular way of life. As a consequence of this, they each ask members some part of Christian life beyond the precepts of the Church.
Fourth, they build up the Church. What they do helps the whole Church not just seeking their private good like a prayer group.
Fifth, they are independent of diocesan and parish structure. They work within it but do not depend upon it. “Before [Pentecost 1998] they were the misfits of the Church. They weren’t religious orders. They weren’t parish organizations. They were lay-driven groups who helped in their parishes while also looking to leadership outside the diocese for direction and inspiration.”
Sixth, from the previous 5, they develop some new form of communion. “The newness that the ecclesial movements contribute to the Church is not so much new forms of mission or new forms of spirituality but new forms of communion.”
Finally there is a criterion of self-identification. This means something can only be a movement if it says it’s a movement.
The name ‘movement’ is attributed to those aggregate realities in which the uniting element is not primarily institutional structure but a ‘vital’ adhesion to some strong ideas and a common spirit.” It is helpful but incomplete. So given all that discussion, the closest thing to a complete definition is: A lay ecclesial movement is an association of the faithful involving primarily lay people in a new form of communion around a particular charism to build up the Church asking certain commitments of Christian life from its members while separate from diocesan and parish structures.