The International Thermal Expansion Symposium was started in 1968 with the initiative of Messrs. R. K. Kirby and P. S. Gaa1. These Symposia cover the deve10pments and advances in theoretica1 and experimental studies of the thermal expansion of so lids and its relation to other re1ated properties, and provide a broad1y based forum for researchers active1y working in this fie1d to convene on a regular basis to exchange their ideas and experiences and report their findings and resu1ts. The Symposia have been se1f-perpetuating and are an examp1e of how a technica1 community with a common purpose can transcend the invisible artificia1 barriers between discip1ines and gather togeth­ er in increasing numbers without the need of national publicity and continuing funding support, when they see something worthwhi1e going on. Of the first five Symposia on1y three pub1ished formal Pro­ ceedings. However, effective with the Sixth Symposium in 1977 when our Center for Information and Numerica1 Data Analysis and Synthesis (CINDAS) of Purdue University became the permanent Spon­ sor of the Symposia, a po1icy of pub1ishing formal Proceedings on a continuipg and uniform basis has been estab1ished. Thus, inc1ud­ ing the present vo1ume, the fo110wing formal Proceedings have been pub1ished: Publisher Symposium Tit1e of Vo1ume and Year and Year 2nd SYMPOSIUM ON THERMAL EXPANSION OF American Institute SOLIDS, Journal of App1ied Physics, of Physics (1970) (1970) 41 (13), pp. 5043-5154 American Institute 3rd THERMAL EXPANSION - 1971 of Physics (1972) (1971) AlP Conference Proceedings No.