This document serves as an overview of the many forms of library twinning, or formal exchanges of materials and/or staff between two institutions. Twinning can be reciprocal, but often involves a one-way arrangement whereby a library in a developing country receives a visit from a librarian of a developed country. Either way, both institutions can benefit from exposure to another culture. The document provides an overview of the benefits and history of library twinning, tips for implementing a binding agreement, and examples of twinning programs. Appendices include a sample request for a twinning partner, prototype memorandum of agreement, addresses and phone numbers of sister city/twinning organizations, an annotated list of book donation programs, samples of staff exchange programs, and a glossary of acronyms. (Contains 36 references.) (BEW)