Aasa, U, Paulin, J, and Madison, G. Correspondence between physical self-concept and participation in, and fitness change after, biweekly body conditioning classes in sedentary women. J Strength Cond Res 31(2): 451–461, 2017—The aims of the study were (a) to investigate the effects of participation in low impact body conditioning classes on physical fitness in sedentary women at different ages and (b) to examine the correspondence between physical self-concept and participation in, and fitness change after, the participation. Ninety-two sedentary women (mean age 44.2 years) participated in 11 weeks of biweekly classes that included cardiovascular, strength, core, endurance, and mobility exercises, all performed in synchrony with music. Cardiorespiratory fitness, maximal lifting strength, mobility, and balance tests were performed before and after the exercise period and the short-form of the Physical Self-Description Questionnaire (PSDQ-S) was completed. Zero-order Spearman correlation analyses showed that women who rated the PSDQ-S dimension sport competence higher participated in a larger number of sessions (rs = 0.24, p = 0.040). At posttests, all participants had increased their balance, the participants aged 20–34 years had increased their lifting strength, and the participants aged 35–65 years had increased their cardiorespiratory fitness and mobility. Most PSDQ-S dimensions did not affect performance change, but the perception of being physically active was related to increased cardiovascular fitness. We conclude that women with a sedentary lifestyle who wish to increase their physical capacity benefit from music exercise and that inquiries about perceived sport competence and physical activity can improve recommendations made by strength and conditioning professionals.