This catalog (Luyten 1979, 1980) is a collection of stars on more than 800 Palomar Proper Motion Survey plates found to have relative annual proper motions exceeding 0.18 arcsec. The motions have been determined by Luyten and his coworkers by either hand blinking and measuring or with the automated- computerized scanner and measuring machine built by Control Data Corporation and located at the University of Minnesota. The new catalog replaces the LTT Catalogues (Luyten 1957, 1961, 1962), wherein stars in the Bruce Proper Motion Survey discovered to have motions exceeding 0.2 arcsec had been compiled. For further information on the NLTT Catalogue itself, including discussions of positional errors, estimation of magnitudes, star designations used in the catalog, completeness, and accuracy of the measured motions, the introduction to the published NLTT (see Volume I) should be consulted. The First Supplement to the NLTT Catalogue (Luyten and Hughes 1980) is the result of continued plate analysis and measurements during printing of the NLTT. The Supplement contains data for 398 stars having motions larger than 0.179 arcsec annually. Duplicate entries were removed from the HEASARC implementation of this catalog in June 2019. This is a service provided by NASA HEASARC .