A study of the energetics of a sururban lawn was conducted in 1972—73 in Walnut Creek, California USA. Several major components of the annual primary and secondary production were measured, including man's role as manager and experimenter in the system. The system was extremely productive with net productivity of 1,020 g/m2 per yr compared to cornfields with productivity of 1,066 g/m2 per yr and exceeding tall grass prairie values of around 1,000 g/m2 per yr. Homopterans, with maximal values of 19 mg/m2 were plentiful; other typical grassland species, like Araneida, were scarce, representing only 1% by weight of the total invertebrate population. Food utilization per unit area by suburban birds considerably exceeded natural grassland bird utilization (46 kcal/m2 per yr vs. 1.01—2.33 kcal/m2 per yr); lawns are ideal foraging sites for open area adapted, flock—feeding species. Man was the dominant consumer in the community, accounting for 10% of the herbivory and nearly 100% of the scavenging. Energy inputs (labor, gasoline, fertilizer, etc.) amounted to 578 kcal/m2 per yr, equalling or exceeding corn production for a comparable net productivity, but not necessarily utilitarian return.