The Peterson Field Guides (PFG) are a popular and influential series of American field guides intended to assist the layman in identification of birds, plants, insects and other natural phenomena. The series was created and edited by renowned ornithologist Roger Tory Peterson (1908–1996). His inaugural volume was the classic 1934 book A Field Guide to the Birds, published (as were all subsequent volumes) by the Houghton Mifflin Company.

The PFG series used what became known as the Peterson Identification System, a practical method for field identification which highlights readily noticed visual features rather than focusing on the technical features of interest to scientists. The series both reflected and contributed to awareness of the emerging environmental movement.

Most books in this series use a section of plates of drawings (usually reduced from commissioned paintings) rather than photographs of the subject species, grouped at the center of the book. This allows for idealized portraits that highlight the identifying "field marks" of each species; such field marks are often indicated by arrows or straight lines in the plate illustrations. However, in several books in this series, the plates consist of photographs (usually without such arrows or indicators), such as in the guides for the atmosphere, coral reefs, rocks and minerals, and the (old Charles Covell 1984 guide to) Eastern moths. In many books in this series (especially older editions), a number of the plates are in black and white. For examples, older editions of the Eastern reptiles/amphibians book had many black and white plates which were colorized for the current edition,Conant, Roger; and Collins, Joseph. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Boston: Houghton Mifflin Co, 1998 pp viii, xii. and the original 1934 Eastern bird book had only 4 color plates. At least one book (insects) was entirely in black and white. However, most newer editions are often full-color (or almost full-color) and tend to be larger. One source claims that the increased size of one of the new editions (Eastern reptiles/amphibians) was considered detrimental to its use as a field guide by its own author and was a publisher decision.

In some cases, new "editions" in this series are entirely new books with completely new texts and illustrations. For example, the fourth edition of the mammals guide has an entirely new text and illustrations by new author Fiona Reid, because the author (William Burt) and illustrator (Richard Grossenheider) of previous editions are both deceased. In fact, Grossenheider died prior to the publication of the previous third edition of 1976.Burt, William H; and Grossenheider, Richard P. A Field Guide to the Mammals of North America North of Mexico. Boston: Houghton Mifflin Co; 1976. p vi. Also, the current Northeastern moths guide by David Beadle and Seabrooke Leckie is an entirely new book than the out-of-print 1984 Eastern moths guide by Charles Covell. The Beadle/Leckie book covers a smaller geographical area and (one author claims) covers moths in greater detail. The old Covell book has been out-of-print for many years, but is currently available through the Virginia Museum of Natural History (which purchased the rights to that book).

The above situation of an old "edition" persisting alongside its intended replacement edition is not unique to the Eastern moths guide. George Petrides' 1988 Eastern trees book (PFG11B) was originally intended to replace Petrides' own 1958 Eastern tree and shrubs (PFG11A) book. However, both books remain popular and the original publisher still offers both books for sale (unlike the case of the old Eastern moths book).

Differences between editions can serve to indicate changes in scientific perspective as well as changes species distribution. For example, the second edition of the freshwater fishes guide by Page and Burr (2011), published 20 years after the first edition, increased the number of species included from 768 to 909, largely due to the addition of previously unrecognized species (114), as well as increased numbers of newly established exotic species (16)."Peterson Field Guide to Freshwater Fishes" Florida Museum of Natural History. flmnh.ufl.edu. Retrieved 2014-08-20. It also expanded coverage of marine fish commonly found in freshwater (19).

The Peterson Field Guides PFG 1: A Field Guide to the Birds (1934), by Roger Tory Peterson Second edition (1939): A Field Guide to the Birds Third edition (1947): A Field Guide to the Birds Fourth edition (1980): A Field Guide to the Birds: A Completely New Guide to All the Birds of Eastern and Central North America Fifth edition (2002): A Field Guide to the Birds of Eastern and Central North America Sixth edition (2010): Field Guide to Birds of Eastern and Central North America, Seventh edition (2020): Field Guide to Birds of Eastern & Central North America, PFG ??: Field Guide to Birds of North America (2008), Second edition (2020): Field Guide to Birds of North America, PFG 1A: Bird Songs (Eastern) (1990)[CD] by the Cornell Laboratory of Ornithology PFG 2: A Field Guide to Western Birds: Field Marks of All Species Found in North America West of the 100th Meridian, with a Section on the Birds of the Hawaiian Islands (1941), by Roger Tory Peterson and Virginia Marie Peterson Second edition (1961): A Field Guide to Western Birds: Field Marks of All Species Found in North America West of the 100th Meridian, with a Section on the Birds of the Hawaiian Islands Third edition (1990): A Field Guide to Western Birds: A Completely New Guide to Field Marks of All Species Found in North America West of the 100th Meridian and North of Mexico PFG 2A: Western Bird Songs (1962) by the Cornell Laboratory of Ornithology Second edition (1992) PFG 3: A Field Guide to Shells of the Atlantic and Gulf Coasts and the West Indies (1947), by Percy A. Morris Second edition (1951) Third edition (1973) Fourth edition (1995), by R. Tucker Abbott and Percy A. Morris; Photos by R. Tucker Abbott PFG 4A: Field Guide to the Butterflies of North America, East of the Great Plains (1951), by Alexander B. Klots PFG 4B: PFG 4A replaced by A Field Guide to Eastern Butterflies (1992), by Paul A. Opler; Illustrated by Vichai Malikul Second edition (1998) PFG 5: A Field Guide to the Mammals: Field Marks of All North American Species Found North of Mexico (1952), by William Henry Burt; Illustrated by Richard Philip Grossenheider Second edition (1964) Third edition (1976) Fourth edition (2006): A Field Guide to Mammals of North America, by Fiona Reid PFG 6: A Field Guide to Pacific Coast Shells, Including Shells of Hawaii and the Gulf of California (1952), by Percy A. Morris Second edition (1966) PFG 7: A Field Guide to the Rocks and Minerals of North America (1953), by Frederick H. Pough and Jeffrey Scovil Second edition (1955) Third edition (1960) Fourth edition (1976) PFG 8: A Field Guide to the Birds of Britain and Europe (1954), by Roger Tory Peterson, Guy Mountfort, and P.A.D. Hollom Second edition (1965), additional authors: I.J. Ferguson-Lees and D.I.M. Wallace Third edition (1974), Fourth edition (1983), Fourth edition, revised and enlarged (1983) Fifth edition (1993), Fifth edition, revised and enlarged (2004), (this was a 50th Anniversary edition, which is sometimes mistakenly referred to as the sixth edition) PFG 9: Animal Tracks (1954), by Olaus J. Murie Second edition (1974) Third edition (2005), by Olaus J. Murie and Mark Elbroch PFG 10: A Field Guide to Ferns and Their Related Families: Northeastern and Central North America with a Section on Species Also Found in the British Isles and Western Europe (1956), by Boughton Cobb and Laura Louise Foster Second edition (1963): A Field Guide to Ferns, Second Edition: Northeastern and Central North America by Boughton Cobb, Cheryl Lowe, and Elizabeth Farnsworth PFG 11A: A Field Guide to Trees and Shrubs: Northeastern and North-Central United States and Southeastern and South-Central Canada (1958), by George A. Petrides Second edition (1972): A Field Guide to Trees and Shrubs: Field Marks of All Trees, Shrubs, and Woody Vines That Grow Wild in the Northeastern and North-Central United States PFG 11B: PFG 11A revised as A Field Guide to Eastern Trees: Eastern United States and Canada (1988), by George A. Petrides; Illustrated by Janet Wehr First edition, expanded [sic]: A Field Guide to Eastern Trees: Eastern United States and Canada, Including the Midwest (1998) PFG 12: A Field Guide to Reptiles and Amphibians of the United States and Canada East of the 100th Meridian (1958) by Roger Conant; Illustrated by Isabelle Hunt Conant Second edition (1975): A Field Guide to Reptiles and Amphibians of Eastern and Central North America Third edition (1991), additional author: Joseph T. Collins, and illustrator: Tom R. Johnson Third edition, expanded (1998) Fourth edition, (2016), additional author: Robert Powell PFG 13: A Field Guide to Birds of Texas and Adjacent States (1960), by Roger Tory Peterson; Illustrations by Roger Tory Peterson PFG 14: A Field Guide to Rocky Mountain Wildflowers from Northern Arizona and New Mexico to British Columbia (1968), by John Craighead, Ray J. Davis, Frank C. Craighead, and Eduardo Salgado Second edition (1996) PFG 15: A Field Guide to the Stars and Planets (1964), by Donald Howard Menzel; Illustrations by Ching Sung Yu Second edition (19??): by Jay M. Pasachoff, Wil Tirion and Donald Howard Menzel; Additional author: Ching Sung Yu Third edition (1992) Fourth edition (2000) PFG 16: A Field Guide to Western Reptiles and Amphibians: Field Marks of All Species in Western North America (1966), by Robert C. Stebbins Second edition (1985): A Field Guide to Western Reptiles and Amphibians: Field Marks of All Species in Western North America, Including Baja California Third edition (2003): A Field Guide to Western Reptiles and Amphibians PFG 17: A Field Guide to Wildflowers of Northeastern and North Central North America (1968), by Roger Tory Peterson and Margaret McKenny PFG 18:This PFG number was used for two field guides. In 1968 this number was Mammals of Britain and Europe by Van Den Brink. This title was dropped from the series in 1985. In 1986 This number became Birds of the West Indies by James Bond. Both of these guides appeared in the Easton Press leather bound copies of the series. For that series the title of the Bond book was changed to "Birds of the Caribbean". :he:קובץ:Birds of the West Indies - James Bond.png Birds of the West Indies (1999), by James Bond

PFG 19: A Field Guide to the Insects of America North of Mexico (1970), by Donald J. Borror and Richard E. White PFG 20: Mexican Birds: Mexico, Guatemala, Belize, and El Salvador (1973), by Roger Tory Peterson and Edward L. Chalif PFG 21: Eastern Birds' Nests: The United States East of the Mississippi River (1975), by Hal H. Harrison, Mada Harrison and Ned Smith PFG 22: A Field Guide to Wildflowers of the Pacific States (1976), by Niehaus and Ripper PFG 23: A Field Guide to Edible Wild Plants of Eastern and Central North America (1977), by Lee Allen Peterson; Illustrated by Lee Allen Peterson and Roger Tory Peterson; Photos by Lee Allen Peterson PFG 24: A Field Guide to the Atlantic Seashore: Invertebrates and Seaweeds of the Atlantic Coast from the Bay of Fundy to Cape Hatteras (1978), by Kenneth L. Gosner; Illustrations by Kenneth L. Gosner PFG 25: Western Birds' Nests: The United States West of the Mississippi River (1979), by Harrison PFG 26: A Field Guide to the Atmosphere (1981), by Vincent J. Schaefer and John A. Day; Illustrated by Christy E. Day PFG 27: A Field Guide to Coral Reefs of the Caribbean and Florida: A Guide to the Common Invertebrates and Fishes of Bermuda, the Bahamas, Southern Florida, the ... (1982), by Eugene H. Kaplan; Illustrations by Susan L. Kaplan