Preliminary unpublished work at the Salt Lake City Laboratory of the Division of Sugar Plant Investigations, Bureau of Plant Industry, United States Department of Agriculture, indicates that beets showing the Y color factor (9) were larger than sugar-beet types recessive for this color factor (y y). It was suggested to the writer that an investigation be made to determine whether or not yield and sugar content were correlated with color factors in beets. Linkages between the R and Y color factors have been reported by Keller (9), and the results indicate a close linkage betwen color factorsR and Y, with about 7.5 percent recombinations. Abegg (1) has found linkage between the R color factor and the factor B for annual habit with a crossover percentage of about 15.5 percent. Unpublished data from the Division of Sugar Plant Investigations indicate several additional color factors in the R Y B linkage group. Yield and sugar analysis, as related to presence and absence of the R factor, have been studied by Nuckols (10). Nuckols' studies were made from a commercial variety and plants recessive for the red color (genotype r r) were separated from plants with red hypocotyls (genotypes R r and R R) at thinning time. He reports no significant difference between the 2 color classes in yield or sugar content. Since these data were taken from a commercial variety of beets by thinning to color classes, no critical information was secured regarding possible genetic linkages; but satisfactory data were secured showing 1 color to be as good as the other as far as production of sugar is concerned. In the present study hybrids were made between a sugar beet and a mangel wurzel. The sugar beet was a high sugar type of genetic constitution R r y y for color. The mangel wurzel was a high yield and low sugar type and of genetic constitution r r Y Y for color. A large F2 population resulting from hybrids between the sugar beet and the mangel made possible a critical study of the association of the R and Y color factors with yield and sugar analysis.