Table of contents for Volume 1.
Short errors (three page PostScript file) for the first printing of Volume 1 corrected in the text of the second printing.
Longer errors (eight page PostScript or PDF file) for the first printing of Volume 1, published in the second printing, hardcover edition of 1997, as Errata and Addenda on pages 319-325.
Supplementary Problems (17 page PostScript file) without solutions for Volume 1. They do not appear in the first printing and are on pages 307-318 of the second printing.
Additional corrections (ten page PostScript or PDF file; version of 10 December 2010) not found in time to include in the second printing.

Errata for volume 1, second edition (version of 20 May 2013).
Table of contents for Volume 2.
Excerpt (27 page PDF file) from Volume 2 on problems related to Catalan numbers (including 66 combinatorial interpretations of these numbers).
Solutions to Catalan number problems from previous link (23 page PDF file).
EC2 Supplement (version of 16 July 2012): supplementary material for Volume 2 (hardcover edition of 1999) including errata, updates, and new material (seventeen page PostScript or PDF file). Many of these corrections have been made in the paperback edition of 2001. For supplementary material not already appearing in the paperback edition, click for PostScript or PDF file (twelve pages). These supplements will be continually updated.
Catalan addendum (Postscript or PDF) (version of 24 May 2013; 94 pages). An addendum of new problems (and solutions) related to Catalan numbers. This addendum will be continually updated. Current number of combinatorial interpretations of Cn: 204 or 205. Why the uncertainty? One of the interpretations is currently a conjecture!
Supplementary problems (without solutions) for Chapter 7 (symmetric functions): 35 page PostScript or PDF file (version of 12 March 2010; 102 problems). New material not appearing in Volume 2.
Painting by Rodica Simion to celebrate the publication of EC2. Original size: 2 3/4" x 4 1/4".
A concordance to all sequences appearing in EC1 and EC2, prepared by Neil Sloane.
The five steps to EC enlightenment (Fan Wei)