Convection associated with Madden-Julian oscillation (MJO) is organized over a broad range of time and space scales within a large-scale envelope of activity. The large-scale envelope of convection is characterized as an eastward propagating disturbance, predominantly of zonal wavenumber 2, which is confined over the warmest waters of the Indian and western Pacific oceans. Large-scale convection is shifted toward the disturbance's temperature anomaly, which appears to result from frictional effects in the boundary layer. Synoptic and mesoscale convective activity is enhanced within the wet phase of the large-scale envelope. The increase at synoptic scales occurs uniformly over all scales, but little difference in the character of the variability is observed between dry and wet phases. The enhanced mesoscale activity within the wet phases exhibits a marked tendency to be organized into westward propagating clusters with periods near 2 days and half wavelengths of about 1000 km. The role of these models for the evolution of the MJO is discussed. ¿ American Geophysical Union 1994