In this project the role of end-users in innovation processes has been investigated in three fields of environmental technology: thermal solar collectors, modern biomass heating systems and ecological buildings. In all three areas Austria takes an internationally leading position with respect to development, production and dissemination and, as it turns out, users do play an important role for the shaping of these technologies. The most striking case are solar collectors (and with limitations also biomass heating), as self-building groups of prospective users had a major influence on a massive distribution of this technology in Austria. This development laid also the ground for a significant growth of export-oriented firms in this sector. The range of user-induced contributions to the development of the technologies investigated comprises the design of new product-types (e.g. solar collectors for self-building), the discovery and experimentation with new kinds of usage (e.g. solar collectors for room-heating), incremental technical improvements (e.g. new control and safety systems for biomass boilers), or the appropriation of unconventional building technologies and building concepts in the course of participative planning processes. Building on empirical investigations and an analysis of existing research, the project identifies specific socio-cultural and technological conditions for the success of user participation. Moreover, strategies for technology policy to better integrate users in technology design are suggested.