Attitudes toward human germline engineering were assessed across three studies. In Pilot Study One, we evaluated participant familiarity ratings for a preliminary item pool consisting of potential targets of germline modification in order to screen out unfamiliar targets. The results were used to screen out 54 of 170 items. In Pilot Study Two, we used participant representativeness ratings to validate categorizations for the remaining items by removing items that were indifferently representative of specific goals (therapeutic or enhancing) and types (physical, cognitive, or personality) of germline modifications. The results also indicated that for many items, the distinction between cognitive and personality characteristics broke down, leading us to collapse these categories into a new type category based on general psychological traits. In Study One, we compared mean approval ratings for potential targets of germline engineering sorted according to the goal of modification (therapeutic or enhancing) and the type of characteristic being targeted (physical or psychological). The results indicated that approval was higher for therapeutic modifications than for enhancing modifications, and higher for modifications targeting physical traits than for those targeting psychological traits. A regression analysis showed that approval correlated positively with knowledge, Big Five Agreeableness, and negatively with perceived risk and female gender. Contrary to expectations, approval did not correlate with psychological essentialism or Big Five Openness. Implications and limitations are discussed.