ratio (squares) derived from the for low-mass, intermediate-mass, and high-mass protostellar systems including data from both this study and the literature (see Appendix C for references). Only D/H ratios derived from interferometric observations are included to minimize effects of beam dilution and to exclude any contribution from larger scales. Also data for low-mass prestellar cores and high-mass starless cores (circles) from the literature (including observations with single dish telescopes) are included. Upper limits are presented as arrows.