My presentation is part of my dissertation supported by Nordic Council and Lincoln Institute of Land Policy. As my research is not complete yet, there are a lot of questions without any answer. I try to concentrate my presentation to the divergence between valuation theory and practice in cases of transitional countries using mass appraisal. I have my own experience from Latvia (1999) and Estonia (1993; 1996; 2001) and it helps me to find some common lines for those countries, which can be similar for some other transitional economies. The property tax is an important fiscal device for countries in transition, and the successful application of mass appraisal is critical to its success. Valuation theory is part of it but it seems that administrative and legal issues are sometimes even more important. As my research is part of dissertation it can be useful to participate in Doctoral Session.