Together with the German-Swiss patron Mariann Steegmann, Rieger founded the Mariann-Steegmann-Foundation, which is dedicated to the advancement of women in music and the arts.
Rieger also was a member of the Advisory Board for the journal Feminist Studies (German: Feministische Studien) from 1988 to 1992.
Rieger was an active participant and jury member at the "Feminist Theory and Music" conference in the United States on several occasions.
Her articles have been published in journals such as Die Musikforschung, Archiv für Musikwissenschaft, Feministische Studien, and others.
She became affiliated with the Homosexuelle Aktion Westberlin (HAW, Gay Action West Berlin) group, which she described as her "salvation.