The concept and practice of “molecular farming” that is the production of specialty protein products in plants is critically reviewed. The major questions pertaining to such applications were identified as being: 1. Which kinds of proteins lend themselves readily to plant-based expression systems? 2. Which plants are most amenable at this time? 3. In which tissues or organs would expression be most efficient? 4. What approaches are available to purify the recombinant proteins? Each of these questions is addressed by means of several examples and some tentative conclusions are drawn. I appears likely that the first products that will emerge from this work will be seed-borne traits which require little or no purification. As purification systems are developed or improved, this will open up the possibility of a wide variety of uses for this technology which should be competitive with traditional fermentation methods. The most sensitive areas for discovery and innovation are delineated and discussed.