This paper describes the design and testing of a wing-box capable of producing wingspan changes for flight speed adaptation developed within the CHANGE project. One of the goals of CHANGE was to design and implement a morphing wing that could combine more than one morphing concept. The capabilities adopted for this wing are span change and leading edge (LE) and trailing edge (TE) camber changes. The last two can produce combinations of positive and negative chordwise camber changes and even spanwise twist. A modular design philosophy was adopted for this wing such that the individual systems producing span change, LE change or TE change can be separately developed and then integrated into the overall wing system. This approach facilitated the development of each required mechanism and made the integration of all components easier. The structure was designed for strength, stiffness and low weight using a structural finite element model. A prototype telescopic wingbox section of 0.6 m in span but with full scale cross-section was manufactured and fitted with the actuation system before full development of the wing system. This prototype was used to validate both the structural design through actual loading and the actuation system’s proper functioning through hundreds of span extension/retraction cycles under load. Results from design and experimental tests demonstrated full functional capability of the telescopic wing-box system.