Richard, I think you missed what Phillip is experiencing here.  If you give users read only access to the folder the database is in, and then they open it, it does lock out other users.  Users need to have read/write access to the folder that the tables, at least, live in.  What I did in this case was two front ends.  They are identical except for the fact that the front end most users are using has all forms set to not allow changes.  So the read/write aspect is handled at the form level.  The editing users have a different front end.  Exactly the same, but the forms allow changes.  Then both sets of users have read/write access to the folder that the back end is in.  Yes, the users could then delete the file or something like that, but very few will ever realize that.  I put the "read only" front end in a different folder, so the typical user doesn't even see the back end, nor ever know it exists or where it is.