Larval development of the nematode, Caenorhabditis elegans, can be arrested by either of two different treatment: (1) complete starvation, or (2) growth in a partially defined culture medium (axenic medium) of strains adapted to bacterial growth. The developmental arrest is complete under total starvation and the starved populations live about 10 days. The developmental block is incomplete in axenic medium; most animals mature but maturation takes 10 times longer than normal. If developmentally arrested cultures are returned to growth on E. coli, both the completely starved and the axenically arrested cultures mature at normal rates. Life-span is prolonged by 1 day for each day of complete starvation; life-span is prolonged by 0.7 days for each day of axenic arrest. These results suggest that aging and development are closely coupled in this system. The results are discussed in terms of previous observations on nutritional deprivation in other invertebrates and caloric restriction in mammals and are interpreted in light of theoretical models of senescence.