This paper analyses the role of damage control inputs in production. Damage control inputs differ from conventional inputs in that they act indirectly or conditionally on output. Their productivity depends on the presence of a damage agent. Examples of damage control inputs include crime and fire protection, flood control and irrigation, disease prevention in people, plarits and animals, and national defense. Agricultural economists, other agricultural researchers and foresters have also studied damage control inputs in pest management models. The indirect action of damage control inputs means that the marginal productivity of this class of inputs depends on their effectiveness in controlling the damage agent, the level of damage agent and the degree of production loss caused by a given level of damage agent. Our analysis shows that increasing returns to the damage control input, in terms of its effect on production, can occur even when the control and damage functions are concave.