Judith Beck herself says that you should start with the pink one - 'The Beck Diet Solution'. The 'Workbook' can be used on its own but there are things in the pink book that aren't in the workbook and it might be a bit confusing to do the workbook in isolation
The green book 'The Beck Diet for Life' is her latest book and actually includes a diet to follow. Can't personally comment on the content cos I haven't seen it, but looking at the reviews on Amazon, they say it's a rehash of the first book plus a diet to follow - and that you're better off with the original book.
I think most of us following Beck here have bought 'The Beck Diet Solution' (the pink one).
Hiya, if anyones interested we've got a little Beck support group thread going in the CD 1000- maintenance section. It's just a few of us who are working through the pink Beck book, and we just help keep each other on track.
Theres an official Beck thread in the Bring Your Head Inside section, but Shanny set up our CD thread because it's different following Beck and a VLCD at the same time. Anyones welcome xx