In this paper, we extend the general assembly line balancing problem by designing an integrated assembly line and addressing the number of workstations and simultaneous assignments of skilled and unskilled workers. We develop a mixed integer program that minimizes the sum of total annual workstation costs and annual salaries of skilled and unskilled workers within a predetermined cycle time. Because this problem is NP-hard, we also develop a genetic algorithm to obtain efficient solutions for large problems. Numerical experiments demonstrate the efficiency of the random key-encoded genetic algorithm.