In previous work on Philadelphia, SIAP found that nonprofit arts and cultural organizations tended to concentrate in economically and ethnically diverse neighborhoods. This paper uses data on for-profit cultural firms to document whether they too cluster in diverse neighborhoods or if they have a different logic of agglomeration. The paper uses two data sets for the five-county Philadelphia region: the nonprofit inventory of over 1,200 cultural providers—including incorporated and “informal” programs—compiled by SIAP in 1997; and a for-profit database of approximately 1,300 cultural firms derived in 1999 from a yellow-pages compilation of selected industries. The paper concludes with a description of five “natural” cultural districts in metropolitan Philadelphia with a focus on the mix of firms in each. It calls for further analysis of the synergies between the for-profit and nonprofit cultural sectors to understand how they share resources—especially audiences and artists—and what sustains these “natural” cultural districts. The implication is that cultural district planning could expand from tourist destinations to arts and cultural production districts.