Prior research has shown that an established organic farm can be as profitable as a conventional farm under certain circumstances. However, organic farming systems often require a transition period before they are fully established after a changeover from conventional farming. Yields may decrease and recover only slowly during this transition period and less profitable crop rotations may be required to establish an organic system. Previous studies have ignored the income trend during the transition phase, and comparisons of organic and conventional farms have been faulted for lack of similarity in management and other resources. The study reported here used a multiyear simulation model to investigate the trend in income of a 117-hectare crop-livestock farm in Pennsylvania (called the Kutztown farm) during this transition process. A baseline model of the Kutztown farm under conventional management (CONB) was found to earn an income (returns over cash operating cost) of $61,900. The transitional models developed were an upper-yield case assuming no yield decline during the transition (TRANS) and a lower-yield case assuming severe yield decline in the first year after the change-over from conventional management and a subsequent linear recovery of yields over a three-year period (TRANS-L). Income was found to be severely depressed by a yield decline during the transitional phase. The first year of TRANS-L resulted in a 43% reduction in income. The scenario without a yield decline (TRANS) resulted in a 13% lower income compared to the baseline (CONB) model. Both transitional models led to an established organic situation with stable organic yields and an income of $57,400 or 7% less than under conventional management. It was found to be more profitable to sell the crops and purchase manure than to feed the crops to beef in a fattening enterprise. At small herd sizes (100 head) the reduction in income caused by the feeding operation was moderate ($1,300), but with a larger operation (213 head) the income sacrifice increased tenfold.