Making strategic decisions based on performance evaluation across wafer fabrication plants in semiconductor manufacturing companies or across companies within the semiconductor industry is challenging because relevant information regarding competitors is not publicly available. One common practice is to analyze the performance of the plant longitudinally. However, as product and process technologies and product mixes change rapidly, the same plant cannot be compared across time periods. In a collaborative research project with a semiconductor manufacturing company, we conceptualized complexity and operationalized it in the form of indexes. We then applied these indexes to the operations of a wafer fabrication plant to assess the changes in its operational complexity on a monthly basis. The indexes proved very useful as inputs to models for evaluating the performance of the plant relative to competition, for formulating cost strategies, and for supporting production planning decisions.