Habitat divergence and negative conspecific-density effects are important mechanisms of maintenance of tree diversity in tropical rain forests. A reciprocal transplant experiment was conducted in a mixed dipterocrp forest in Sarawak, Malaysia, to analyze between-species differences in effects of soils and conspecific density on seedling mortality and herbivory. Seedlings of ten habitat specialist species (clay- vs. sand-soil species) were planted on sandy and clayey soils in a high- or low-conspecific-density; half of the seedlings were treated with herbicide and pesticide. The rates of survival, growth and herbivory were measured over 14 months. Mortality rates of clay- and sand-soil species were higher on the sandy and clayey soils, respectively, suggesting habitat effects were important for coexistence of the two habitat specialist groups. Herbivory rates were higher on the clayey soil, in the high-conspecific-density, and without herbicide and pesticide treatment. There were no significant interacting effects between species' habitats and the other variables on herbivory rates. This may indicate that negative conspecific-density effects are important in species diversity within a habitat but not between different habitats.