Greg,
What kind of password are you looking for? If you want one that won't let
someone just open the DB and mess around with the tables, you can create a
small form and use it as the Startup form (Tools -> Startup -> Display form)
On the form's load event, use an input box that asks for a password, then
checks the password against a constant you have set in a module.
If Inputbox("Enter a password") = yourPassword Then
DoCmd.Close acForm, "Form1"
Else
Application.Quit
End If
It's a simple way to go about it and will keep the casual user from messing
with anything. There are a few ways to secure your DB that are much harder
to deal with, unfortunately I can't help you with those.
HTH,
Nick