The Superpave mix design system was one of the major products of the Strategic Highway Research Program (SHRP). While implementation of this new technology began in the mid-1990s, a major question that has remained to be addressed was whether constructed Superpave pavements would meet design expectations. Furthermore, with the emergence of improved mechanistic-empirical performance prediction models, actual pavement response and performance data were needed to calibrate and validate such models. To address these concerns, the Pennsylvania Department of Transportation (PennDOT) initiated a major five-year research program with Penn State entitled "Superpave In-Situ Stress/Strain Investigation" (SISSI). The main objectives achieved under the SISSI project included instrumentation of several pavements throughout the Commonwealth of Pennsylvania, direct measurement of the response of Superpave asphalt pavement sections to vehicle loading and environment, direct evaluation of distresses developed in pavements using Superpave mixes, and collection of the data for validation of mechanistic-empirical design models and validation of the integrated climatic models for pavement design. The work included an extensive effort toward instrumenting eight pavement sites throughout the Commonwealth of Pennsylvania. Instrumentation took place during pavement construction to minimize interference to common and normal paving operations. Four of the selected sites were full-depth new construction or reconstruction. The project resulted in the collection of a vast amount of diverse data, on which various types of preliminary analyses have been conducted. Several potential uses exist for these data, including investigating the relationship between the observed performance of the placed Superpave mixes and the properties of the materials used in these mixes. The data can also be used toward the calibration and validation of the models used in the Mechanistic-Empirical Pavement Design Guide, including the Enhanced Integrated Climatic Model. Volume I of this report is the Final Report; Volume II presents additional data as appendices.