This study examines Great Britain's adaptation in the 1920s and 1930s to the decline in the market for its nineteenth-century exports: cotton textiles, ships, iron and steel products, and coal. Continued growth in a mature economy depends at certain points upon structural change, in this case a movement from declining to expanding industries. At such times, I contend, the developing sector tends to grow independently, rather than through transformation of existing productive structures. Growth does not occur primarily through a reallocation of capital and labor from declining to expanding industries and regions.