Thanks Patrick. I did some additional testing following your response, on a brand new PC, Win 7, fresh InfoPath 2007 install, MOSS 2007. I started with a new form template and new Forms Library and received the same results. However, this time I tested with a Decimal field as well and that did work fine end-to-end. It appears that some support of the Integer/Whole Number format is being dropped in InfoPath 2010. At this point, it means that existing InfoPath 2007 forms with integer fields would need those fields converted to Decimal if they are converted to IP 2010 format forms. The 2007 integer fields still work in the form, but they cannot be modified at the Data Connection level (i.e. can't add to or remove from DC). The integer-format field from the IP 2007-format form built via IP 2010 and published to MOSS 2007 does not appear as a Column under the Form Library Settings, but does appear in the default View.