These ecumenical characterizations intentionally downplay the fact that the term “mechanism” is used differently in different scientific and philosophical contexts (see Levy 2013 and Andersen 2014a,b for alternative overviews of the differences). Indeed, much of the progress in the early years involved learning to recognize the many ways that the term “mechanism” can be used and the many commitments that can be undertaken in its name. (For still other characterizations of mechanism, see Woodward (2002), Fagan (2012), Nicholson (2012), and Garson (2013)). Taking these ecumenical views as a starting point, we now consider the four basic components: 1) the phenomenon, 2) parts, 3) causings, and 4) organization.