Mark A. Findeis and a panel of active researchers present their best methods not only for preparing, handling, and characterizing gene delivery agents, but also for gene delivery. To help those preparing and characterizing gene transfer agents, the contributors examine a broad range of compounds that bind with DNA to form the compact condensed phases that facilitate cellular delivery—among them peptide conjugates, synthetic polymers, and lipids. They also outline specific approaches to gene transfer in vivo, including direct delivery by intratumoral injection and indirect delivery by cell-specific targeting of DNA complexes, and discuss in detail many spectroscopic techniques for characterizing nonviral gene delivery agents.