This tutorial book presents six carefully revised lectures given at the Spring School on Datatype-Generic Programming, SSDGP 2006, held in Nottingham, UK, in April 2006, colocated with the Symposium on Trends in Functional Programming (TFP 2006), and the Conference of the Types Project (TYPES 2006). All the lectures have been subjected to thorough internal review by the editors and contributors, supported by independent external reviews. The volume is opened with a comprehensive assessment of different sorts of parametrisation mechanisms in programmming languages, including how they are implemented, leading up to the notion of datatype genericity. After the introduction of datatype-generic programming the volume contains the following topical chapters: comparing approaches to generic programming in Haskell; generic programming, now; generic programming with dependent types; generic programming in Omega; and revealing the X/O impedance mismatch.