Published herein are the papers presented at the second annual AFCRL Scientific Balloon Symposium covering the advances shown in balloon design, materials, instrumentation, meteorology, and scientific applications since the last symposium held in Boston on 25, 26 and 27 September 1963. Balloon technology presentations include stress studies, new balloon films, sensing elements, telemetry systems and a new balloon locating system. Applications and experience in working with tethered, meteorological and sounding balloons are discussed. In addition, information is presented on such existing programs as BAL-AST, and Surveyor and such proposed projects as the "AFCRL Stratospheric Humidity Program" and "The Mars Balloon."