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Interest in climatic variability on time-scales of decades to centuries has grown rapidly in the last five years. Some of this interest has been engendered by the need to gain a better understanding of natural climatic variability in order to resolve more clearly the climatic signature of enhanced greenhouse warming. However, this focus on decadal and interdecadal fluctuations in climate has also been driven by a growing realisation that other known climatic features, such as the El Niño Southern Oscillation (ENSO) phenomenon, show distinct signs of being modulated by lower frequency variations in climate. The search is on to resolve distinct climatic signals on decadal to century time scales, to identify the physical mechanisms underlying them, and to incorporate any influences of such climatic signals on ENSO into current seasonal climate forecasting schemes. The book Beyond El Niño: Decadal and Interdecadal Climate Variability provides a useful first step in any assessment of the range of current research and level of scientific understanding concerning decadal to interdecadal climatic fluctuations. It is part of a growing effort aimed at documenting research findings in this area, and their implications for our understanding of the climate system and long range forecasting approaches. Overall, this book addresses the topic in six initial chapters on observational evidence and analyses, followed by the remaining eight chapters devoted to numerical modelling studies and theoretical interpretations. Being essentially a report of scientific research efforts under the European Commission’s Decadal and Interdecadal Climate Variability Experiment (DICE), there is naturally a strong emphasis throughout the book on the northern hemisphere. The bulk of chapters focus on the North Atlantic and North Pacific Ocean basins and in regions such as India and North Africa. However, there are chapters that look to the Tropical Atlantic and Pacific, and one on observational findings from analyses of historical global sea-surface temperature data. Beyond El Niño: Decadal and Interdecadal Climate Variability is a book for the research scientist working in the area, or in related fields, who is interested in following the progress of decadal to interdecadal climatic variability research or wishing to examine its impact on a particular region. This area of research is still evolving, to the extent that there is no overall consensus about nomenclature or a complete picture of the climatic features being resolved. Beyond El Niño: Decadal and Interdecadal Climate Variability illustrates something of the scope of the task still required to develop a unified physical understanding of decadal to interdecadal climatic variability. Several chapters in this book discuss differences between ENSO and decadal to interdecadal signals over various regions of the globe. However, the book stops short of any discussions about the possible modulation of ENSO by lower frequency fluctuations in the climate system. This is to be expected, as such linkages are still being examined and debated, while the scope of this book is specifically to look beyond ENSO. It is an indication that research in this area is still in its infancy, and to gain a full measure of current research findings one needs to examine a number of publications. Overall, Beyond El Niño: Decadal and Interdecadal Climate Variability provides a useful summary of some of the research effort that is being undertaken around the world to document and understand decadal to interdecadal climatic variability. By the very nature of this research, it is difficult to envisage a current book being published that would cover the full range of the subject matter. This will change over time, much as it has for books dealing with ENSO. I would recommend Beyond El Niño: Decadal and Interdecadal Climate Variability to researchers wishing to add to their understanding of decadal to interdecadal climatic variability. Further publications on this topic in the future will add to the material discussed in this book.