Frederick

US precedes. Pantheon, New York, 1967 is the true first; a 1968 Caldecott Honor Book and a New York Times Best Illustrated Children's Book for 1967. Lionni followed his editor Fabio Coen from Obolensky to Pantheon, which is why the titles from Swimmy (1963) onward are Pantheon rather than Obolensky/Astor books. German-language editions — Frederick is heavily collected in Germany — are translations postdating the New York first, not the original. Later Knopf and Dragonfly Books reissues are reprints.