Proceedings of the 14th International Conference on Hyperfine Interactions and 18th International Symposium on Nuclear Quadrupole Interactions, HFI/NQI 2004, held in Iguazú Falls, Brazil, 5-10 August, 2007. This volume focuses on the most recent studies on all aspects of hyperfine interaction detected by nuclear radiation and nuclear quadrupole interactions detected by resonance methods in the areas of materials, biological and medical science, as well as on contributions on new developments in instrumentation and methods, ab initio calculations and simulations. This volume comprises research papers, reviews, and short communications recording original investigations related to: Theory on Hyperfine Interactions (HFI) and Nuclear Moments; Magnetism and Magnetic Materials (Bulk and Thin Layers); HFI probes in Semiconductors, Metals and Insulators; Lattice Dynamics and Ion-Solid Interactions; Surfaces, Interfaces, Thin Films, and Nano-structures; Resonance Methods; Nuclear Moments, Nuclear Polarization and Spin Dynamics; Investigations in Biology, Chemistry, and Medicine; New Directions and Developments in Methodology. The papers present the latest scientific work of various invited speakers and contributor researchers from the five continents that have brought their perspectives to the meeting.