The R project webpage provides a succinct description of the R language and environment.

At the start, one might want to look at the official R manual An Introduction to R.

Another gentle introduction to R is R for Beginners by Emmanuel Paradis.

The Use R! series of books by Springer is particularly helpful for R.

*The New S Language*by Richard A. Becker, John M. Chambers, and Allan R. Wilks (Chapman & Hall, 1988), a.k.a. the "Blue Book"; covers S version 2*Statistical Models in S*by John M. Chambers and Trevor J. Hastie (Chapman & Hall, 1992), a.k.a. the "White Book"; covers S version 3*Programming with Data*by John M. Chambers (Springer, 1998), a.k.a. the "Green Book"; covers S version 4*Software for Data Analysis: Programming with R*by John M. Chambers (Springer, 2008)*Modern Applied Statistics with S, 4th Edition*by William N. Venables and Brian D. Ripley (Springer, 2002)*S Programming*by William N. Venables and Brian D. Ripley (Springer, 2000)*Introductory Statistics with R, 2nd Edition*by Peter Dalgaard (Springer, 2008)*Data Analysis and Graphics Using R, 2nd Edition*by John Maindonald and John Braun (Cambridge, 2003)*Using R for Introductory Statistics*by John Verzani (Chapman & Hall/CRC, 2005)*The R Book*by Michael J. Crawley (Wiley, 2007)*Statistics: An Introduction using R*by Michael J. Crawley (Wiley, 2005)*Statistical Computing: An Introduction to Data Analysis using S-Plus*by Michael J. Crawley (Wiley, 2002)*A Handbook of Statistical Analyses Using R*by Brian Everitt and Torsten Hothorn (Chapman & Hall/CRC, 2006)*Statistical Computing with R*by Maria L. Rizzo (Chapman & Hall/CRC, 2008)*A First Course in Statistical Programming with R*by W. John Braun and Duncan J. Murdoch (Cambridge, 2007)*Data Manipulation with R*by Phil Spector (Springer, 2008)*The Basics of S-PLUS, 4th Edition*by Andreas Krause and Melvin Olson (Springer, 2005)*Introduction to Probability with R*by Kenneth Baclawski (Chapman & Hall/CRC, 2008)*Probability and Statistics with R*by María Dolores Ugarte, Ana F. Militino, and Alan T. Arnholt (Chapman & Hall/CRC, 2008)*R in a Nutshell, 2nd Edition*by Joseph Adler (O'Reilly, 2012)*Learning R*by Richard Cotton (O'Reilly, 2013)*A Beginner's Guide to R*by Alain F. Zuur, Elena N. Ieno, and Erik Meesters (Springer, 2009)*Introduction to Scientific Programming and Simulation Using R*by Owen Jones, Robert Maillardet, and Andrew Robinson (CRC Press, 2009)*Probability with Applications and R*by Robert P. Dobrow (Wiley, 2014)*Statistics and Data with R*by Yosef Cohen and Jeremiah Y. Cohen (Wiley, 2008)*R Cookbook*by Paul Teetor (O'Reilly, 2011)*The R Software*by Pierre Lafaye de Micheaux, Rémy Drouilhet, and Benoit Liquet (Springer, 2013)*Understanding Statistics Using R*by Randall Schumacker and Sara Tomek (Springer, 2013)*R by Example*by Jim Albert and Maria Rizzo (Springer, 2012)*The Art of R Programming*by Norman Matloff (No Starch Press, 2011)*R in Action, 2nd Edition*by Robert I. Kabacoff (Manning, 2014)*Introductory R*by Robert J. Knell (2013)- R: A language for data analysis and graphics by Ross Ihaka and Robert Gentleman, Journal of Computational and Graphical Statistics, 5(3):299-314, 1996
- Lexical scope and statistical computing by Robert Gentleman and Ross Ihaka, Journal of Computational and Graphical Statistics, 9(3):491-508, 2000
- Data Analysts Captivated by R's Power by Ashlee Vance, New York Times, January 6, 2009
- R You Ready for R? by Ashlee Vance, New York Times, January 8, 2009
- R for SAS and SPSS Users by Robert A. Muenchen (Springer, 2008)

- The R Manuals (I find the R Reference Index particularly helpful. It is a 9 MB download with 3500 pages.
- Contributed Documentation
- Books related to R
- Publications related to R
- R News (2001 to 2008) and R Journal (2009 to present)

- R Homepage (The R Project for Statistical Computing)
- CRAN (The Comprehensive R Archive Network)
- Mailing Lists
- FAQ
- Related Projects