The true first edition carries FIRST EDITION and the printing code M-E (indicating December 1955 as the printing date) on copyright page. The book is light blue cloth with black spine and gold letters. The jacket carries a price of $3.50. The book title on the jacket spine is red when it is in fine condition, but tends to fad to pink if sunned.
Note: Early printings lack the FIRST EDITION statement, and have different printing codes indicating the month and year when they were printed. The first letter indicates the month and the second letter indicates the year. The months range from A to M where A is January, B is February, C is March, and so forth through to M, which indicates December. J is skipped for some reason. The years are represented by the second letter which can be A through Z, and once again the letter J is skipped. Thus the letters represent a 25 year span, after which the letters repeat.
To use the code on the first Edition of Profiles of Courage as an example, the M means December, and the letter E can either indicate 1955 or 25 years earlier - 1930. Since we know Kennedy didn't write the book in 1930 (because he would have been 13 years old), we have to conclude that E represents 1955 in this case. Here are some later printing codes that people have asked about:
A-F = January 1956
D-F = April 1956
H-F = August 1956
C-G = March 1957
Profiles In Courage book won the Pulitzer Prize for Biography.
To find the market value for this book, click on the pre-filled eBay, AbeBooks, or Biblio links to the right and look for comparable listings that have all of these first edition points.