The present study aimed to examine the relationship between perfectionism, OCD symptom dimensions, harm avoidance, and incompleteness at varying levels (i.e., higher-order/subscale) in college students. College students ( n = 548) completed measures of perfectionism, obsessive-compulsive symptoms, harm avoidance and incompleteness. The results revealed that all five higher-order dimensions of perfectionism were related to incompleteness but only three were related to harm avoidance. Parallel mediation revealed an indirect relationship between concern for mistakes and doubts about actions and checking and cleaning behaviors, respectively, through incompleteness. An indirect relationship between concern for mistakes and doubts about actions with ordering, respectively, through both incompleteness and harm avoidance was found. However, incompleteness played a stronger role than harm avoidance in this relationship. These results suggest that incompleteness might be a stronger motivator than harm avoidance for perfectionistic individuals. Therefore, interventions targeting incompleteness should be implemented to potentially circumvent the development or worsening of obsessive-compulsive symptoms.