This research investigates mortality differentials in Eastern Europe, a region known for its excessively high adult mortality. It employs a unique longitudinal data set covering the entire population of Bulgaria from the census of 1992 until 1998. It focuses on differences in mortality between Muslims, a large and disadvantaged minority group, and non-Muslims. Virtually nothing is known about the health conditions of Muslims in Europe. Preliminary tabulations suggest that Muslims in Bulgaria have adult mortality levels that are below the national average despite their severe social and economic disadvantages. Hypotheses are developed that attribute this puzzle, similar to the "Hispanic paradox" in the United States, to life-style factors and to social relations. The detailed information available on causes of death will be instrumental in distinguishing the factors involved. A dramatic economic downturn during the period under study will also help to identify factors affecting mortality. Non-parametric hazards models will be employed to test hypotheses. The research should help to identify reasons for the very high and rising mortality in Eastern Europe and to illuminate the health conditions of a large and growing minority population. More generally, it bears upon the relative explanatory power of materialist and social/behavioral approaches to the study of adult health and mortality.