The present study examines the problem of fortis and lenis in approximately 150 dialects of southern Germany, Austria, German-speaking Switzerland, Alsace, and the German-speaking minorities in Italy, Hungary and the former Czechoslovakia and Yugoslavia. The Upper German dialects are of particular interest from this point of view, because voice and aspiration, the features traditionally associated with strength, are generally absent. Changes related to strength such as lenition, vowel lengthening, simplification of geminates, and sandhi phenomena receive special attention. The findings are put into their appropriate context by comparison to the results of research on the status of strength in standard German and the modern Germanic languages. Although the realization of strength is language-specific and varies according to word-position, it can be equated with consonant length in standard German and Upper German dialects.