Flexural stiffness or effective width of floor slab acting as coupling beam is very important for the analysis of Coupled Shear Wall (CSW) systems. New generation of high performance concretes provide an alternative to conventional concrete to enhance the performance of coupling slabs. This research investigates the flexural behaviour of coupling slabs incorporating Engineered Cementitious Composite (ECC) compared to conventional Self-Consolidating Concrete (SCC). The high strain capacity and low crack width makes ECC an ideal material for coupling slab. Non-linear coupling action of ECC slabs is investigated experimentally with small-scale models having variable geometric parameters under monotonic loading. The performance is judged based on moment-rotation response, flexural stiffness/effective width, deflection, cracking, strain development and failure modes. Design charts for flexural stiffness/effective width of coupling slabs are presented in pre-cracking/cracking/post-yielding stages. CSW systems with ECC are found stronger and ductile than their SCC counterparts confirming the viability of constructing such structures.