Understanding the transport and mixing in the tropical upper troposphere is important for understanding the distributions of water vapor and ozone. Here we use trajectory calculations and meteorological analyses to examine the transport in the southern subtropics, focusing on the transport from convective to non-convective regions and from the stratosphere into the troposphere. The dependence of this transport on the basic state (in particular, the strength of the tropical "westerly ducts") and phase of ENSO is examined. The results of the trajectory calculations are compared with available observations of water vapor and ozone.