My topic is the confluence of two recently active philosophical research programs. One research program concerns the metaphysics of realization. Within the literature on realization there is substantial disagreement about even the general outlines of a theory. Occasionally it seems that the only common ground is that realization is a dependence relation that sometimes or always relates entities that figure in different explanatory schema, such as those of the special sciences and those of more fundamental sciences. The other research program concerns scientific explanation in terms of mechanisms. According to the advocates of the “new mechanism” there is a distinctive and important kind of scientific explanation that is generated by discovering and describing causal mechanisms. There is some dispute about whether this kind of explanation is genuinely distinctive. And there is much dispute about how exactly to characterize mechanisms. But even most critics of the new mechanism do not wish to replace it with old fashioned deductive-nomological explanation.