I've just got the book "Brewing Classic Styles" by Jamil Zainasheff
All of the recipes are geared to 7 gallons --- now on page 35 he talks about adjusting down to a 5 gallon recipe doing a 3 gallon boil.
The text reads (using 3 gal): Boil all of your hops in half of your total malt extract, in half the recipe volume, add the remaining extract at the end of the boil to pasteurize it, and then dilute to the final recipe volume in the fermenter.
So this is a dumb question --- I guess you cut all the ingredients in half - even the malt extract. Only concern here is if I cut the extract in half and then compare the modified Jamil recipe to the type of recipe I'm looking at in other books (already adjusted for 5 gal) --- the amount of extract seems pretty light.