The contributions in this volume provide a snapshot of the latest research and future plans for space-borne and ground-based experiments dedicated to the observation of the gamma-ray sky. The articles are authored by both seasoned veterans of the first dedicated gamma-ray missions, and young scientists entering the fascinating field of gamma-ray astrophysics. With the advent of gamma-ray instrumentation on spacecraft and large and sensitive ground-based detectors, new and unexpected phenomena have been discovered, such as gamma-ray bursts and gamma-ray emission from blazars. The immense vitality of the field in the current ?post-EGRET era? is witnessed by the numerous ongoing and forthcoming gamma-ray experiments documented here, complementary to various cosmic-ray, neutrino, astroparticle and X-ray projects.

Detectors for High-Energy Gamma-Rays: Functional Tests and Performance Characterization During the Assembly Phase of the Modules of the AGILE Silicon Tracker (M Basset et al.); Gamma Air Watch (GAW) -- An Imaging Atmospheric Cherenkov Telescope with Large Field of View (T Mineo et al.); Topics in Fundamental Physics: Frontiers of High Energy Cosmic Rays (M Pimenta); Dark Matter at -Rays (L Pieri); Populations of Subhalos in Cold Dark Matter Halos (E Bisesi); Multiwavelength Observations: WEBT Multifrequency Support to Space Observations (C M Raiteri & M Villata); REM -- The Remote Observatory for GRB et al. (E Molinari); INTEGRAL Three Years Later (L Foschini et al.); Poster Session: Gamma-Ray Burst Physics with GLAST (N Omodei); Observations of Blazars and EGRET Sources with INTEGRAL (V Vitale et al.); Pulsar Spectrum: Simulating Gamma-Ray Pulsars for the GLAST Mission (M Razzano et al.); and other papers.