This study identifies the unique contributions of asthma severity, symptoms, control and generic measures of quality of life (QoL) to asthma-specific QoL, as measured by the 12-item RAND Negative Impact of Asthma on Quality of Life scale (RAND-IAQL-12).Using a sample of 2032 adults with asthma, we conducted multiple regression analyses that sequentially examined hypothesised predictors of asthma-specific QoL. The change in variance accounted for and total unique variance accounted for is calculated as hypothesised predictors are added in each step.Our results indicate that asthma severity and asthma symptoms are strong predictors of asthma-specific QoL only when not controlling for aspects of asthma control. In regression models that include other aspects of asthma control, the contributions of both asthma symptoms and severity were substantially reduced, with asthma control and aspects of QoL related to social roles and activities emerging as the strongest predictors of asthma-specific QoL.These findings suggest that researchers measuring the impact of asthma on QoL should also consider the importance of asthma control as measured by the RAND Asthma Control Measure (RAND-ACM) and generic QoL scales that measure aspects of daily life that are uniquely affected by asthma.