Reinforced concrete (RC) walls are frequently used as lateral stiffness and strength-providing members in RC buildings. If well detailed and designed according to capacity design rules, RC walls can lead to a very robust behavior and stable cyclic response under seismic loading. Moreover, they are often better suited to control inter-story drifts than RC frames, limiting hence better than frames the extent of non-structural damage. Recent earthquakes in Chile (2010) and New Zealand (2011) revealed, however, several unexpected failure modes of RC wall buildings which have not been accounted for in design. Ongoing research projects at the Earthquake Engineering and Structural Dynamics Laboratory of EPFL address some of the observed failure modes. The paper describes ongoing research projects, presents first results and discusses future research needs with regard to the seismic design of RC walls.