Think about what you want to do
If a certain condition is met then
'******you want to do something
Endif

HTH
John

Use Boolean values (True/False) not String values.
    ProductReceived: IIf([Quantity]=[QtyReceived],True,False)

Kevin, This turns the field to -1 in the query but does not check the box in the form

Access SQL or MS SQL?

Access

Screenshots of Query and Form?

SELECT CribPODescription1T.QtyReceived, CribPODescription1T.Quantity, IIf([Quantity]=[QtyReceived],True,False) AS ProductReceived, CribPODescription1T.POID, CribProductT.CLCPartNumber, CribProductT.Description, CribPODescription1T.PartNumber, CribPODescription1T.CLCProductID, CribPODescription1T.ProductReceived1
FROM CribPODescription1T LEFT JOIN CribProductT ON CribPODescription1T.CLCProductID = CribProductT.CribProductID;

Your ProductReceived field is in a *table*.  To enter true/false values into the table, this is not how you do it.  Making a query that calculates the true/false as you have done does *not* automatically enter the true/false value into the table -- because the table isn't "aware" that you've run the query.  To have a query actually update a table, you need to use an update query.

OK, Was kind of afraid of that.  Thanks everyone for your help