Thanks Paul. Most of my Session state variables are either simple integer numbers, or one word "strings". As I mentioned, they are created and at the first opportunity, e.g., a Cancel, or Save event, I put in:
Session.RemoveAll
to clear them out. I have found that inserting is much faster with Session variables than say, inserting data from form textboxes (the former: 2 secs per records over a 24K bps connection, the latter, 6 seconds).
I suppose when you can use Querystrings without a problem, such as passing 12-15 numbers to the next aspx page, is probably preferable. But my observations are that Session variables are handled quite smoothly and very fast - so I suppose you want to use them when you can without jeopardizing performance --