Annals of the International Geophysical Year, Volume XIII: Tables of IGY Monthly Median Ionospheric Data, Part I is the first of the five volumes of IGY data containing tables of monthly median value of ionospheric characteristics for the period of July 1957 to January 1959 inclusive. The data are extracted from booklets, bulletins, and data summaries of many kinds which have been prepared at ionospheric observatories and sent to one of the Discipline V World Data Centers at Boulder, Moscow, Slough and Tokyo. The stations are arranged in alphabetical order and the tables for each station are preceded by some of the more important information relating to the station. This book will prove useful to geophysicists, historians, and researchers.