The Sun is the only star from which matter can be collected in order to investigate its elemental and isotopic composition. Solar elemental abundances provide the most important benchmark for the chemical evolution of the galaxy. They can be derived from photospheric observations, from in situ investigations of the solar wind, and from solar energetic particles. Solar isotopic abundances provide an important reference for the galactic evolution and if available with sufficient precision, also for the chemical and physical evolution of the solar system. The abundances of isotopes in the solar atmosphere can only be inferred from in situ observations of solar particles. This review makes an attempt to summarize current knowledge about the composition of the solar wind and shows how the elemental, isotopic, and charge state composition of solar wind particles is shaped as the solar corona expands throughout the heliosphere. ¿ 2000 American Geophysical Union