A.Microeconomic capital goods theory was utilised to provide a theoretical framework on which a dynamic econometric model was based. Econometric procedures were then employed in an analysis of sheep producers' decision making regarding the annual supplies of wool, lamb and mutton, and annual changes in the inventory levels of sheep, lambs and ewes maintained for breeding purposes.Estimates show that wool prices provide the long-run stimulus for increases and decreases in the sheep flock while mutton and lamb prices are responsible for short-run changes in flock composition. Substitution between sheep and beef cattle is of considerable importance although no significant substitution between sheep and cropping could be found. Seasonal conditions proved to be an important short-run supply shifter, affecting both numbers and composition of the sheep flock.Introduction This study focuses on annual production and inventory decisions of Australian sheep producers by modelling producer behaviour in the context of capital theory. The central theme of the paper is simple. Sheep are considered to be capitai goods and producers are viewed as portfolio managers. In any period the producer of a good is faced with the problem of maximising some objective function (profit, utility) given some level of input costs, an anticipated output price and an initial stock of capital (fixed productive resources).In the livestock sector there are factors other than prices that impinge upon production; e.g. seasonal conditions and biological constraints on output. Thus, any model which purports to explain a production decision within the livestock sector must explicitly account for all three elements of that decision; i.e. the demographic constraint, the economic decision and the modification of the decision caused by exogenous influences. The model outlined in this paper is intended to account for each