Foreign function interfaces are an important feature of many modern languages allowing programmers to interface with libraries (especially system libraries) not otherwise available in the programming language. Chez Scheme has long supported an interface for defining foreign procedures, accessing foreign data, and defining Scheme procedures that can be called by foreign functions. This interface provides easy access to basic C data types and procedures that make use of them, but is more difficult to use for structured data commonly used in C functions. The foreign-type or ftype system, provides a flexible way for accessing and mutating structured data, including support for C’s structs, unions, and bit fields. Ftypes can be used when defining foreign procedures and Scheme procedures callable from C, making it easier to interface with C functions that make use of these features. In this talk I will demonstrate the new ftype functionality and describe its implementation.