This doctoral dissertation deals with the decline and the transformation of mortality in Styria ? the so-called epidemiological transition. The thesis was developed as part of the FWF research project P-21157 ?The First Demographic Transition in Austria 1869-1937? (syn. GAFP). As part of this project an extensive digitization of available and relevant data to describe the demographic transition in Austrian crown lands was carried out. Based on this data, this dissertation attempts to analyse the mechanisms of transition in morbidity and mortality at the level of the political districts. Besides the application of various statistical methods, several qualitative-historical sources were evaluated. In the first part of the thesis, the social and economic environment is clarified on the basis of previous research findings. These findings are supplemented by the author?s research with a focus on Styria. In the second part, an approximate periodization of the phases of the mortality decline for Styria is defined and mortality trends based on the criteria of gender and age are examined. Special emphasis is given to the development of infant and child mortality. In the third part of the thesis the development of the cause of deaths is investigated, in particular the common infectious diseases such as tuberculosis, pneumonia, diphtheria, whooping cough, dysentery, typhoid fever, smallpox, measles and scarlet fever. For all of these, the observed decline and the regional spread are mapped and in some cases plausible explanations for the decline are offered. Not all aspects of the mortality decline have been clarified. To obtain further insights into the area under investigation future research should be based on individual data (eg., medical records or death registers).