Trichoderma spp. have served as models for asexual reproduction in filamentous fungi for over 50 years. Physical stimuli, such as light exposure and mechanical injury to the mycelium, trigger conidiation; however, conidiogenesis itself is a holistic response determined by the cell's metabolic state, as influenced by the environment and endogenous biological rhythms. Key environmental parameters are the carbon and nitrogen status and the C : N ratio, the ambient pH and the level of calcium ions. Recent advances in our understanding of the molecular biology of this fungus have revealed a conserved mechanism of environmental perception through the White Collar orthologues BLR-1 and BLR-2. Also implicated in the molecular regulation are the PacC pathways and the conidial regulator VELVET. Signal transduction cascades which link environmental signals to physiological outputs have also been revealed.