International, national, and subnational laws and policies call for rapidly decarbonizing energy systems around the globe. This effort relies heavily on renewable electricity and calls for a transition that is: (i) 

flexible

 enough to accommodate existing and new electricity end uses and users; (ii) 

resilient

 in response to climate change and other threats to electricity infrastructure; (iii) 

cost-effective

 in comparison to alternatives; and (iv) 

just

in the face of energy systems that are often the result of—or the cause of—procedural, distributive, and historical injustices. Acknowledging the intertwined roles of technology and policy, this entry provides a cross-disciplinary review of how microgrids may contribute to renewable electricity systems that are flexible, resilient, cost-effective, and just (including illustrative examples from Korea, California, New York, the European Union, and elsewhere).