How is language change effected and how does it proceed? In this article the central concepts of Rudi Keller's much-quoted work "Sprachwandel: von der unsichtbaren Hand in der Sprache" ("On Language Change. The Invisible Hand in Language") are introduced and the main criticism presented. Following this first part, Keller's theory of language change is related to the concrete example of linguistic changes in job advertisements. The main interest here is in the enhancement of job titles ("Gebrauch von aufwertenden Berufs- und Personenbezeichnungen"). 26,000 job advertisements from 1950 to 1999 are analysed in the empirical part. The advertising copies show, for example, a clear increase in the use of "Mitarbeiter" resp. "Mitarbeiterin" ("employee") instead of "kaufm. Angestellte" ("clerk"), "Fabrikarbeiter" ("factory worker"), "Magazingehilfe" ("storeman") or the like. The second part of this article shows how this aspect of language change can be understood through Keller's Invisible-Hand model.