Posted you an e-mail reply as I had your w/book with sample data!

"Dan the Man" wrote:

I have a spreadsheet entitled "New Rule Clients", and a spreadsheet entitled
"Old Rule Clients". Column A of both spreadsheets lists clients by "last
name", and Column B lists clients by "first name".

I am no longer adding names to the "Old Rule Clients", however every now and
then, a new client (added to the New Rule Clients spreadsheet) previously
received services at my agency (they were listed on the Old Rules
spreadsheet), and I want to identify them (be aware that they previously
recieived services) in order to pull their old files.

My two options that I'm trying to decide upon a

1) Create an additional column next to the last name and first name columns
(column c) which has a formula that would produce a flag advising me that a
client entered onto the "New Rules" spreadsheet was previously entered onto
the "Old Rules Spreadsheet":

A B C

Doe John SEE OLD RULE FILES

2) Use some sort of conditional formatting to highlight or change the font
when a client entered on the "New Rules" spreadsheet is "matched" to a client
who was previously entered on the "Old Rules" spreadsheet (again advising me
to check the Old Rules Spreadsheet in order to locate their file).

I'm just not sure which way would be most efficient (between the options I
thought of above), and what the accompanying formula would be to address this
need.

Any help would be appreciated?

Dan