I have a rather lengthy form for which I would like to be able to control the order in which the fields(controls) are filled in.
How can I force the user to enter data into the 1st control before moving on to the 2nd control and so on?
I also would like to generate appropriate error messages explaining why the user is not being allowed to continue when they fail to enter data into a control.
Any help would be greatly appreciated.

They way i do it is to disable a control until the previous control has been completed look at enable in the help files

disabling the other controls works for the first time the form is used...but after it seem s that the controls remain enabled what should I do. I tried setting it up so that the controls are disabled On Open of the form but it still does not work.

I would re-think this requirement. Your users may find it more annoying than helpful. You can put final edit code in the Form's BeforeUpdate event to make sure that all fields are properly populated. If any errors are found, you can cancel the update, display an error message, and set the focus back to the first field in error.

The problem with checking the fields at the end of the proccess is that I have two list boxes whose contents are determined by the re -query of a combo box. In order to keep these list boxes up to date I used the Me!Refresh method. If users start entering data out of sequence the required(date) field generates errors.

Why not hide the List boxes untill data entry complete?

Try adding "not null" in the validation property.Let me know if this is what you're asking.