Diurnal cycle of convection over summertime continents starts with the formation and subsequent growth of a well-mixed convective boundary layer from the early morning temperature and moisture profiles as the surface sensible and latent heat fluxes increase after sunrise. It proceeds with the formation of shallow convective clouds as the convective boundary layer deepens, and leads to the eventual transition from shallow to deep precipitating convection around local noon. This problem is notoriously difficult to represent in large scale models of weather and climate, even with the so-called convection-permitting models that are becoming routinely used in NWP. This talk will present a model intercomparison case that I developed about a dozen years ago that is still being used to explore various aspects of the transition. Selected results from several studies using this setup, the most recent by Kurowski et al. (under review in J. Atmos. Sci.) will be discussed.