This study is a partial evaluation of the effects of the U.S. Plant Variety Protection Act of 1970 (PVPA). It attempts to determine the effect of the Act on expenditures on crop breeding by the private sector, and on the availability and productivity of soybean varieties. A number of other potential effects of the Act, some of them controversial, are mentioned but not addressed in this study. The findings were that both the number of non-hybrid crop breeding programs and expenditures on them increased substantially during the 1970s as compared to the 1960s. It seems likely that these phenomena are due to the incentives created by the Act. Examining the productivity of breeding efforts in soybeans, the study found a three-fold increase in the number of varieties submitted for yield tests in the 1970s as compared to the 1960s. It also found the rate of improvement in yields was greater for varieties released after 1970 than for those released before 1970, although the improvement was significantly different from zero only at the 16 percent confidence level.