'Peckinpah: The Western Films - A Reconsideration' by Paul Seydor (University of Illinois Press, 1980; revised edition 1997). Scholarly, erudite, rigorously analytical and requiring of the reader that their hearts and minds be fully engaged with the films under discussion, Seydor's 400-page opus is quite simply one of the most important books of film criticism ever published. An affirmation of Peckinpah as a great American artist (Seydor had the courage to publish the first edition at a time when Peckinpah's reputation was at its lowest), this is not just great film writing - it's a profound and deeply cerebral work of literature in its own right.
'Sam Peckinpah: If They Move ... Kill 'Em!' by David Weddle (Faber, 1996). Pushing 600 pages, this is everything that a biography should aspire to - meticulously researched, clear sighted and anchored in the interrelationship between its subject's life and creative output - as well as being compellingly readable.
'Peckinpah: A Portrait in Montage' by Garner Simmons (Limelight Editions, 2004 - 3rd edition). Acclaimed by David Weddle as "still giving us the fullest documentation of the making of each of the films". (Thanks to J.D. at Radiator Heaven for the heads up on this title. Simmons knew Peckinpah while he was alive which, as J.D. points out, "gives his book considerable credibility".)
'Bloody Sam' by Marshall Fine (Miramax, 2006 - reissue). Available again after a spell out of print, Fine's book - as the title suggests - is concerned with Peckinpah's public image as a hard-drinking, hard-brawling and generally hard-boiled badass. Which is fine (as a wise man once said: when the legend becomes fact, print the legend), but this does the director few favours in terms of objective re-evaluation.
'The Pocket Essential Sam Peckinpah' by Richard Luck (Pocket Essentials, 2000). Succinct and often colloquial, Luck nevertheless finds enough room within the slim perameters of a Pocket Essentials title (about 100 pages) to identify the key thematic concerns of Peckinpah's filmography, fill in some entertaining background detail and deflect a few of the brickbats (violence for its own sake; misogyny) that are still hurled at Sam's films.
'The Films of Sam Peckinpah' by Neil Fulwood (B.T. Batsford, 2002). It's bad form to self-publicize, but while it's by no means the best bit of Peckinpah-lit you could add to your bookshelf (that honour goes to Seydor with Weddle coming in an honorable second), I'm mighty proud of my contribution to the small canon of books on Peckinpah. Read this and Richard Luck's title for a solid introduction, then move on to the real meat of Seydor, Simmons and Weddles' books.