  The study of collision events with missing energy as searches for the dark
matter (DM) component of the Universe are an essential part of the extensive
program looking for new physics at the LHC. Given the unknown nature of DM, the
interpretation of such searches should be made broad and inclusive. This report
reviews the usage of simplified models in the interpretation of missing energy
searches. We begin with a brief discussion of the utility and limitation of the
effective field theory approach to this problem. The bulk of the report is then
devoted to several different simplified models and their signatures, including
s-channel and t-channel processes. A common feature of simplified models for DM
is the presence of additional particles that mediate the interactions between
the Standard Model and the particle that makes up DM. We consider these in
detail and emphasize the importance of their inclusion as final states in any
coherent interpretation. We also review some of the experimental progress in
the field, new signatures, and other aspects of the searches themselves. We
conclude with comments and recommendations regarding the use of simplified
models in Run-II of the LHC.
