This chapter discusses the determination of national income and its distribution in a closed economy. It introduces the production function and factors of production, capital and labor. It explains that total output is determined by factor supplies and technology. Factor prices, the wage rate and rental rate, are determined by supply and demand in factor markets. Total income is distributed to factors based on their marginal products. The chapter then covers the components of aggregate demand - consumption, investment, and government spending. It presents the loanable funds market model to show how interest rates adjust to equilibrate saving and investment.