Kim Rooney Hagelstein teaches Applied Horn and directs the Horn Choir at Tarleton State University. In addition to teaching, Hagelstein performs regularly as Second Horn of the Waco Symphony Orchestra and Principal Horn of the Temple Symphony Orchestra. In previous years, Hagelstein has performed both domestically and abroad with the groups including the Lone Star Wind Orchestra, Eurobrass, the Carl Rosa Opera Company, and the New Sigmund Romberg Orchestra.

Hagelstein can be heard on recordings by the Lone Star Wind Orchestra, Eurobrass, and the Cincinnati Pops. As a soloist, Hagelstein has performed with the Lone Star Wind Orchestra, the Tarleton State University Wind Ensemble, the McLennan Community College Wind Ensemble, the University of Missouri University Philharmonic Orchestra, and the Northland Symphony Orchestra. She has also presented performances at regional and international horn workshops.

Hagelstein has degrees from the University of Missouri-Columbia and the University of Cincinnati College-Conservatory of Music, where her primary teachers included Randy Gardner, Marcia Spence, Duane Dugger, and Elizabeth Freimuth.