Delaware has long attempted to provide business structures that reflect the demands of the business community in an efficient and productive manner. One prime example of this demand/response is the "series" interest available in Delaware limited partnerships, LLCs, and statutory trusts. The series structure combines the flexibility that different types of businesses desire along with the statutory and contractual support that Delaware provides to all of its unincorporated business organizations. Other states have now emulated the Delaware series concept, although there is still considerable confusion as to how a series works. This piece provides an overview of some of the more significant provisions of the Delaware series law. The author concludes that the Delaware series provides a beneficial, efficient use of a combined contractual Delaware entity form with sensible, informed planning