Quality of service adaptability refers to the ability of components/services to adapt in run-time the quality exhibited. A composition study from a quality point of view would investigate how these adaptable elements could be combined to meet system’s quality requirements. Enclosing quality properties with architectural models has been typically used to improve system understanding. Nevertheless these properties along with some supplementary information about quality adaptation would allow us to carry out a composition study during the design phase and even to predict some features of the adaptability behavior of the system. Existing modeling languages and tools lack enough mechanisms to cope with adaptability, e.g. to describe system elements that may offer/require several quality levels. This paper shows how we reuse existing modeling languages and tools, combine them and create new ones to tackle the problem of quality of service adaptability and composition. The final goal of this work is to evaluate architectural models to predict system’s QoS behavior before it is implemented.