The goal of the AMAST conferences is to foster algebraic methodology as a foundation for software technology, and to show that this can lead to practical mathematical alternatives to the ad-hoc approaches commonly used in software engineering and development. The first two AMAST conferences, held in May 1989 and May 1991 at the University of Iowa, were well received and encouraged the regular organization of further AMAST conferences on a biennial schedule. The third Conference on Algebraic Methodology and Software Technology was held in the campus of the University of Twente, The Netherlands, during the first week of Summer 1993. Nearly a hundred people from all continents attended the conference. The largest interest received by the AMAST conference among the professionals extended to include the administration organizations as well. AMAST'93 was opened by the Rector of the University of Twente, followed by the Local Chairman. Their opening addresses open this proceedings, too. The proceedings contains 8 invited papers and 32 selected communications. The selection was very strict, for 121 submissions were received.