Challenges for long-lived massive particle searches at the LHC

The most recent studies by the CMS and ATLAS collaborations are presented on the sensitivity to searches for long-lived massive particles. Such particles appear in several extensions of the Standard Model and are allowed by the present bounds coming from cosmology and existing accelerator data. We show the challenges to event triggering and reconstruction posed by such particles, and how CMS and ATLAS plan to deal with them. Particular emphasis is given to possible early discoveries, i.e., with 100 $pb^{-1}$ or less. In special cases, long-lived particles may come to rest in dense material, and decay at much later times; these can be searched for by triggering during periods with no beam-beam collisions.