Keith,
Yes, this is certainly possible, but a bit tricky.
You first need to select the grid column that is to hold the checkbox. To do so, select the column from the drop-down list at the top of the property window. Then drop a checkbox onto the column. At first, it looks like it didn't work, but in fact the checkbox is present, but hidden behind the existing textbox.
To remove the textbox, select it in the drop-down list, then click on the title bar of the form designer itself (not the form, the form designer). This is necessary because you would otherwise de-select the textbox. Finally, press the Delete key.
You will now see the checkbox in the designer. But when you run the form, you will only see it in the selected row. If that's not what you want, set the column's Sparse property to .F.
Hope this helps.
Mike
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Mike Lewis (Edinburgh, Scotland)
My Visual FoxPro site: www.ml-consult.co.uk