Sea level rise is one of the major long-term consequences of human-induced climate change. Future projections of sea level changes and their regional expression are of crucial importance for the sustainability of coastal settlements around the world. The Fourth Assessment Report of IPCC (AR4) had comprehensively assessed key processes contributing topast, present and future sea level changes. However, process understanding was limited and thus both size and uncertainties associated with some of these contributions remained still largely unknown. This also hampered the overall projections of global mean sea level rise in AR4. The future dynamical behaviour of the large polar ice sheets of Antarctica and Greenland in a changing climate was identified as the primary origin of the large uncertainty in the AR4projections of sea level rise for the 21st century.IPCC Working Group I (WGI) has acknowledged the relevance of this specific topic and thus (1) proposed a chapter on 'Sea Level Change' in its contribution to the IPCC Fifth Assessment Report (AR5) and (2) organized a targeted IPCC Workshop on 'Sea Level Rise and Ice Sheet Instabilities' very early in the assessment cycle for the IPCC's AR5. ThisWorkshop took place in Kuala Lumpur, Malaysia, from 21 to 24 June, 2010. The Workshop brought together experts from very diverse disciplines with a wide range of expertise, covering oceanography, ice sheet dynamics, glacier research and hydrology to discuss latest results from both observations and modelling relevant for sea level change. The workshop structure included a combination of plenary sessions with invited keynote presentations, group discussions, poster sessions and, finally, topical breakout groups.This Workshop Report contains a concise summary of the overall discussions and conclusions of the Workshop as well as summaries of the discussions in the breakout groups. It further includes the extended abstracts of the keynote presentations and poster abstracts presented during the Workshop.