ENSO is the dominant source of interannual climate variability in the tropics and across the globe. Understanding ENSO's dynamics, predicting El Niño and La Niña, and anticipating changes in ENSO's characteristics and impacts are thus of vital importance for society. This session invites contributions regarding the dynamics of ENSO, including multi-scale interactions; low frequency, decadal and paleo ENSO variability; ENSO theory; ENSO diversity; ENSO impacts on climate, society and ecosystems; ENSO teleconnections; seasonal forecasting of ENSO; and climate change projections of ENSO. Studies aimed at understanding ENSO in models of a range of complexity are especially welcomed, including analysis of CMIP model intercomparisons.