In this paper, we demonstrate that the main standard optimization techniques dependency directed backtracking and model merging can be adapted to description logics with concrete domains. We propose algorithms for these techniques for the logics ALC(D) and ALCRP(D). Important results of this study are (1) a new requirement for concrete domains in order to enable dependency directed backtracking for all clash types of description logics with concrete domains, and (2) the flat and deep model merging techniques can be fully adapted to ALC(D) but their applicability to the logic ALCRP(D) is limited. 1 Motivation In recent years dramatic advancements in developing new optimization techniques for expressive description logics (DLs) have been achieved. The requirements derived from practical applications of DLs ask for more expressive languages. It is well-known that reasoning about objects from other domains (socalled concrete domains, e.g. the real numbers [1]) is very important for practi...