Mechanism schemata are one of the least understood parts of MDC's account of mechanistic explanation. Relatedly, there is a common misconception that there is no place for abstraction in MDC mechanisms. These two problems can be remedied by looking more carefully at what MDC say both in their 2000 paper and elsewhere about schemata and abstraction, and by following up on a comment of Machamer's indicating that Piaget was the inspiration for schemata. Darden's work on mechanism discovery reveals an important role for abstract mechanism schemata, not only as concise representations of known mechanisms, but also as hypotheses for how unknown mechanisms might work. Piaget's schemata likewise both capture the developing child's current state of knowledge, and serve as templates into which new experiences are fit. If we assume that mechanistic explanations should pick out real difference-makers, and that what makes a difference needn't always be fine-grained details, we open up an explanatory role for abstract schemata to play. Schemata represent the coarser-grained features of mechanisms that are often among the most important difference-makers. In many contexts they might need to be supplemented with finer grained details in order to give an adequate explanation, but independent of those details, schemata remain explanatory in virtue of being part of the explanation. Detailed accounts of real difference-makers need not be seen as in competition with abstract models or generalizations. They can (and should) be combined in mechanistic explanations.