This list is not complete and never will be.  Exceptions can be made probably with every publisher but this will help you identify most first editions with most publishers.

Number line examples:  10 9 8 7 6 5 4 3 2 1 = first printing

                                     10 9 8 7 6 5 4 = 4th printing

                                     2 4 6 8 10 9 7 5 3 1 = first printing

                                     4 6 8 10 9 7 5 3 = 3rd printing

                                     10 9 8 7 6 5 4 3 2 = 1st printing for Random House!  (No "1")

ANDREWS AND MCMEEL  No identification in first editions; later reprintings are usually identified by stating the printing, and the date of the printing.

APPLETON (aka Appleton-Century-Crofts) Number 1 surrounded by brackets on last page of book on their classic old titles.  Since the early '80s, they have adopted a number line.

ATHENEUM Prior to 1986, first ed. are stated; since then, they have used a number line.

ATLANTIC MONTHLY PRESS Date on title page same as copyright page.  Prior to 1925, there is no way of knowing for sure

BANTAM number line

BLACK SPARROW PRESS Check colophon page.  many have no indication of printing but title pages on first editions are in color

BOBBS-MERRILL inconsistent, check for bow and arrow at bottom of copyright page, after 1936 the books state first edition 

BONI & LIVERIGHT Subsequent printings are identified

JONATHAN CAPE, LTD.  First editions are stated

CHATTO & WINDUS LTD  Subsequent printings are identified

CHRONICLE Subsequent printings are identified

CROWN Before mid 1979 first editions not identified, but subsequent printers were.  After that, number line and statement of printing

DELACORTE PRESS  originally part of Dell, then subsequent editions were stated, then either a statement of first ed. or number line

DELL  states date of first publication, no indication of other printings

DIAL PRESS  first editions stated

DODD MEAD & CO  before 1976 no effort was made to identify printing history!  sometimes they stated first printings and subsequent prints, after 1976 they used a number line

DORRANCE & CO Subsequent printings are identified

DOUBLEDAY  First editions are stated

DOUBLEDAY DORAN & CO  First editions are stated

DOUBLEDAY PAGE & CO  first editions are stated

E. P. DUTTON & CO  before 1976, first editions not identified, at which point they were stated on the copyright page.  Subsequent printins were always identified

ECCO PRESS  first editions are stated

FABER & FABER  Subsequent editions are stated

FARRAR STRAUS & GIROUX First editions are stated

DONALD I FINE a number line is used

DAVID R GODINE first editions are stated

GROVE PRESS editions are stated

JOHNNY GRUELLE CO  no indication of printing at all

HAMISH HAMILTON first ed. are stated before 1976, then subsequent ed. are stated

HARCOURT BRACE & CO subsequent editions stated, first ed. often but not always, have a 1 on copyright page prior to the 1930s, afterward, first editions are stated

HARCOURT BRACE JOVANOVICH first editions stated

HARPER & BROTHERS first editions stated

HARPER & ROW  both stating first editions and using a number line.  in mid 1970s the number line usually appeared on the last page of the book

GEORGE G HARRAP & CO on copyright page is line reading "First published..." reprints are indicated.

WILLIAM HEINEMANN states "first published..." with reprinting indicated as such

HODDER & STOUGHTON before 1940s, no indication of printing was made.  After, printings are dated and first printings are usually (not always) stated

HENRY HOLT & CO before 1945, no regular method used.  In general, look for a date of printing, which often indicated first edition; on many titles, subsequent editions were stated.  After '45, first editions are stated.  Since '88 the company has also used a number line.

HOLT, RINEHART, AND WINSTON First editions stated

HOUGHTON MIFFLIN CO Title pages are dated on first editions; afterward, dating is dropped and copyright page indicated printing.  In recent years a number line is used.

ALFRED A KNOPF up to mid '30s, first ed. was not indicated but subsequent printings were.  Afterward, first ed. stated.

J. B. LIPPINCOTT states first edition; often also has a number line

LITTLE BROWN & CO early 20th century, first editions were indicated by a date line on the copyright page, indicating first publication.  Subsequent printings added additional date lines.  More recently, first ed. are stated, and a number line used.

LIVERIGHT PUBLISHING early volumes from this publisher only indicate subsequent printings; more recently a number line has been used

MACMILLAN (after '76 MACMILLAN PUBLISHING) states "Published" with original date.  Subsequent printings are noted below on copyright page.  Since '36, first ed. were indicated; since '79 a number line has been used.

METHEUN books state "first published in..." Subsequent reprints are so noted

WILLIAM MORROW & CO first printings are stated (usually); subsequent printins are always stated.  More recently a number line used, with the number on the far right of the line indicating the year of publication "1 2 3 4 5 94 93 92 91 90" to show that the book first appeared in 1990.

MYSTERIOUS PRESS first ed. are stated and number line is used

NEW DIRECTIONS before '70 no indications of printing was made.  After that, first printings were stated.

W. W. NORTON & CO first ed. are stated, a number line is also used.

PANTHEON BOOKS subsequent printings are identified; first printins are usually, but not always stated.

PENGUIN uses a number line and the statement "first published..."

PETER PAUPER PRESS early peter pauper books were limited editions; a statement of limitation indicates that the book is a first ed.  More recently, there has been no identificatiion used.

PLATT & MUNK no identification has been used

PRENTICE-HALL first ed. are stated, wither by "first Edition" or the use of a number line

PRICE STERN SLOAN first ed. are stated.  Prior to the late '80s, books said "first edition" on the copyright page, more recently, this has been replaced by the use of a numberline.

PUTMAN Subsequent Ed. in early Putman Books were usually (not always) stated.  First ed. should have a date on title page.  More recently, a number line was used

RANDOM HOUSE First editions of Random House books are stated.  However, a number line is also frequently used.  Random House number lines only go down to 2.  Therefore, a statement of "First Edition" combined with a number line stopping at 2 indicates that the book is a true first.

REILY & LEE After 1937, first ed. are stated.  Prior, there was no regular method used.

ROUTLEDGE & KEGAN PAUL State "First Published" on copyright page, with the date agreeing with the copyright date.

ST. MARTIN'S PRESS No indication is given as to the printing of a book

CHARLES SCRIBNER'S SONS Prior to 1930, there was no indication of printing given, although on some titles you can check to see if the date on teh copyright page matches the one on the title page.  After 1930, there was the adoption of the now famous Scribner's A.  From the 1930s into the 1970s, first editions were identified by the appearance of a capital A on the copyright page.  After 1972, there is still an A, but there is also a number line.

SHEED & WARD Subsequent editions are stated

SIMON & SCHUSTER Subsequent editions are stated on early Simon & Schuster books; also see if the date on the copyright page agrees with the date on the title page.  A number line was added in the 1970s

GIBBS SMITH First Editions are stated

PEREGRINE SMITH Prior to 1980, there were no indications of edition.  Afterward, date on copyright page and title page should match

STEIN & DAY Subsequent ed. are noted

VAN NOSTRAND REINHOLD A number line was used

VIKING PRESS Subsequent editions are stated.  More recently, a number line has been used on many (but not all) titles

WARNER BOOKS First editions are stated

NOTE:  Most new publishers not listed will state subsequent editions, state first editions and or use a number line, but of course this is not always true for everyone!