Beetle - thanks for quick reply.

This solution works, but it's not ideal - here's why.  
The very first field on my form is a Parcel ID number which is required.  
Once that number is entered the first time, I would like it to be locked.  
Here's the catch: there are a number of other fields on the form that, in
practice will be populated over the course of time.  Some may be filled in
right away, when the Parcel ID number is first entered, some may be filled in
weeks later, and some may need to be edited several years later.  The forms
current event affects all of these controls and I would like it to only
affect the first one (Parcel ID).

- mjg