This study investigates whether illness representations predict changes in asthma control or vice versa. Illness perceptions and asthma control were assessed in N = 113 asthma patients at the begin/end of an inpatient rehabilitation. Bivariate cross-lagged panel analyses showed that the illness representation dimensions Personal control, Consequences, Coherence, and Emotional representation predicted the change in asthma control, but asthma control did not predict illness representations.