The diversity of form in the Actinomycetales is well-recognised, due to the sustained generation of environmental isolates for pharmaceutical screening. Actinomycetes isolated from soil and related substrates show primary biodegradative activity, secreting a range of extracellular enzymes and exhibiting the capacity to metabolise recalcitrant molecules. Composting is one process which relies heavily on such prolific actinomycete activity. Amongst actinomycetes in soil, there are examples of different strategies, from cycles of rapid proliferation and sporulation to the maintenance of populations by prolonged slow growth and scavenging, and the evidence for this is examined. The mechanisms of lignocellulose degradation by actinomycetes are discussed in relation to functional conservation within the group, and correlations with those described in other bacteria and fungi.