During the time that the Northern Laboratory has been actively investigating shell materials and other agricultural residues we have been in direct communication with operators of shell grinding plants; some of these have been visited. We have received numerous letters and calls for information and assistance in solving grinding problems, or in using the ground products. Through these contacts and our experiences we have learned much about the factors that lead to success or failure in this utilization. Ten plants are now producing a variety of ground shell products useful in both agriculture and industry. When the Northern Laboratory was organized, only one plant, established originally by the California Walnut Growers Association, was grinding nut shells. This plant, following a number of operational difficulties and administrative changes, now processes 40 tons or more of shells per day and produces a wide variety of ground products including exceedingly fine flours for use in plastics and plywood adhesives. It has been said that this plant processes all of the English walnut and apricot pit shells and 80 percent of the peach pit shells available in California. The Laboratory has attempted to determine the amount of shells and pits available commercially in different areas. Data of this nature has been obtained for the larger cracking plants but there are many small operations for which we lack this information. "Agricultural Statistics" compiled and published annually by the U. S. Department of Agriculture provide an excellent source of information regarding production and, in many cases, the disposition of farm commodities. For example, the production of pecans in 1951, presented by states, totaled more than 73,000 tons for the 10 states reported. However, no data were available regarding marketings in-shell, or the quantities remaining on the farms or in the orchards. Thus, the quantity of pecan shells actually available for processing can be determined only through surveys of cracking plants. Only limited information is available concerning black walnut shells and this has been obtained through the cooperation of shellers or crackers. In some areas fruit pits, such as apricot and peach pits, accumulate at canneries or freezing plants. Similarity in character of the pit shells to those of the nuts permits their use in plants grinding nut shells. Thus, the supply of raw material in any area may be augmented by inclusion of fruit pit shells.