The Natural Radiation Environment Symposium (NRE VII), the Seventh in the NRE series, which commenced forty years ago in 1963 at Rice University Texas, was held in Rhodes (Greece) in May 2002. During the intervening four decades the research work presented at these NRE Symposia has contributed to a deeper understanding of natural radiation and in particular of its contribution to human radiation exposures.It is clear from the quality and diversity of the 143 papers in this volume of Radioactivity in the Environment series that the study of the natural radiation environment is an active and continually expanding field of research. The papers in this volume fall into a number of main and topical research areas namely:- the measurement and behaviour of natural radionuclides in the environment- cosmic radiation measurement and dosimetry- the external penetrating radiation field at ground level- TENR (Technologically Enhanced Natural Radiation) and NORM (Naturally Occurring Radioactive Materials) studies- assessment of the health effects of radon- regulatory aspects of natural radiation exposuresIn these papers the results of many new surveys of natural radionuclide levels in the environment and of improved methods of detection are described. While some of the natural radiation sources investigated are unmodified by human activity, many accounts are given here of exposures to natural sources which have been enhanced by technology. Such TENR and NORM exposures are shown to range from activities such as mining, oil and gas exploitation, the use of industrial by-products as building materials, to space travel to name but a few. In several cases quite high doses to some individuals are shown to occur. Accounts are given here of methods to prevent and reduce exposures to such sources.