The Western Tropical Pacific (WTP) is a region where sea surface temperatures reach their highest values. Its warm waters are the source of intense convective systems, and the associated latent heat release acts as an important forcing for planetary waves across the whole globe. SST variability in the WTP, although weaker in amplitude than the variability in the central and eastern part of the tropical Pacific, has the potential to affect atmospheric teleconnection on a variety of scales. On the sub-seasonal scale, WTP SST affects the intensity and propagation of organized convection within the MJO and other modes of tropical low-frequency variability. On the interannual time-scale, the monsoon systems of East and South Asia are affected by WTP anomalies, as well as the planetary waves propagating into the northern extra-tropics. On the interannual time scales, variations in zonal and meridional gradients of SST in the WTP region affect long-term changes in the Walker and Hadley circulations, and links with decadal variability in the North Pacific and the North Atlantic have been explored by many scientists. The aims of the proposed five-day workshop are to review the current knowledge on the origins and consequences of variability in the WTP, and discuss the ability of the latest generation of coupled GCMs to simulate such variability and teleconnections.