Multi-storey timber buildings are becoming internationally more and more common. The thriving forces behind this trend involve the sustainable aspects of the material and the rapid development of innovative engineered timber elements. An example of an engineered timber element are crosslaminated timber (CLT) panels. CLT panels consist of cross-wise glued layers of timber to obtain panels that can be used as wall and floor elements. Another innovative trend is the modular construction method. This method is based on the prefabrication of modules as building compartments, which can be stacked on-site to form a cellular building type. Reasons for this trend, are the increased building speed and the benefits of repetitive fabrication in a controlled environment. The first application of a modular multi-storey timber building is Hotel Jakarta in Amsterdam, for which construction started in 2016. This building was the reason for this master thesis, in which the following question was formulated. What is the structural behaviour of a cross-laminated timber module system, how can it be designed and is it possible to construct a ‘self-supporting’ system of modules for a tall timber building? In order to answer the research question, a literature research has been done to investigate the aspects involved with tall timber buildings, modular construction, the material cross-laminated timber and the connections. Then a universally applicable module with a concrete floor slab and CLT walls and ceiling elements was specified. A design case of 8 modules in height and 8 modules in width, placed onto a concrete podium structure, has been investigated. To examine the structural behaviour of the modular assembly in terms of deformations and force distribution a 3D finite element model was made. Then, by using the obtained knowledge, resistance calculations have been made to find the critical limits for this design case. For this design case it was proven that a multi-storey modular cross-laminated timber building composition is a structurally viable solution. The limiting factors for maximum building height and maximum slenderness are, the fire situation in relation to buckling of the side wall, the connection strength of the stabilization wall and the maximum deformation due to rotation of the stabilization wall involving bending of the floor and ceiling element.