Contribution1 DLHA:DarkMatterLesHouchesAgreement Coordinator: Csaba Balázs, David G. Cerdeño, Rebecca Leane, Mitsuru Kakizaki, Sabine Kraml, Christopher Savage, Pat Scott, Sezen Sekmen, AMIDAS: Chung-Lin Shan, DarkSUSY: Lars Bergström, Torsten Bringmann, Gintaras Duda, Joakim Edsjö, Paolo Gon- dolo, DMFITandDMMW: Stefano Profumo, Tesla Jeltema, DRAGON: Carmelo Evoli, Daniele Gaggero, Dario Grasso, Luca Maccione, FeynRules: Claude Duhr, Benjamin Fuks, GALPROP: Igor Moskalenko, Elena Orlando, Troy Porter, Andrew Strong, ISAJET: Howie Baer, micrOmegas: Genevieve Bélanger, Fawzi Boudjema, Alexander Pukhov, PPPC4DMID: Marco Cirelli, Mario Kadastik, Paolo Panci, Martti Raidal, SLHA: Sven Kreiss, Frank S. Thomas, Semi-analyticalpropagationmodels: TimurDelahaye, FiorenzaDonato, JulienLavalle, David Maurin, PierreSalati, Richard Taillet, SuperIsoRelic: AlexandreArbey, Farvah Mahmoudi Abstract This work presents a set of conventions and numerical structures that aim to provide a universal interface between computer programs cal- culating dark matter related observables. It specifies input and output parameters for the calculation of observables such as abundance, di- rect and various indirect detection rates. These parameters range from cosmological to astrophysical to nuclear observables. The present con- ventions lay the foundations for defining a future Les Houches Dark MatterAccord. 1 INTRODUCTION Over the last decade a burst of activity has surrounded various dark matter related problems. As a byproduct of this activity, a number of robust numerical tools have been created by par- ticle, astro-particle and astrophysicists. These tools predict values for observables that, when contrasted with observation, can shed light on the properties of dark matter. The dark matter relatedcomputercodesaddressawiderangeofphysicalproblems,ofwhichthemostimportant are: 1. derivingFeynmanrulesfromLagrangians, 2. calculatingscatteringamplitudesfromFeynmanrules, 3. buildingcrosssectionsordecayratesfromamplitudes, 9