Proto-Slavic, the reconstructed ancestor of the Slavic languages, presents a rich inflectional system inherited from Proto-Indo-European. In this handbook all the inflectional endings of Proto-Slavic are traced back to Proto-Indo-European through a systematic comparison with the corresponding forms in related languages.Applying a redefinition of Proto-Slavic based on prehistoric loanword relations with neighbouring non-Slavic languages, Thomas Olander provides a new look at the Proto-Slavic inflectional system. The systematic, coherent and exhaustive approach laid out in the handbook paves the way for new solutions to long-standing problems of Slavic historical grammar.