A convincing detection of gamma-rays from annihilation of dark matter particles would be a stunning scientific achievement. The GLAST satellite, to be launched early next year, would offer a good chance of detecting them. To make sure that we are detecting gamma-rays from dark matter and not from the other astrophysical sources such as blazars, we should not rely only on one method -- the mean energy spectrum -- but also on the other signature -- anisotropy on the sky. In this talk I will describe a novel technique that we have developed recently for detecting gamma-rays from dark matter that traces the large scale structure of the universe, through anisotropy in the diffuse Cosmic Gamma-ray Background.