Rationale. Treatment for children with obsessive compulsive disorder (OCD) involves deliberative approach of feared situations via exposure and response prevention, however a substantial proportion of youth do not respond. One potential explanation for the failure of deliberative approach of feared situations to result in complete symptom reduction may be that patients also have prepotent, or automatic response tendencies to not approach or to avoid feared stimuli. Measures of automatic approach and avoidance biases have been developed and examined using standardized pictorial stimuli among populations with fairly homogenous fears. However, the highly heterogeneous nature of OCD symptoms suggests the need to utilize idiographic stimuli. The current pilot study represented an attempt to demonstrate initial feasibility, reliability, and preliminary validity of an idiographic measure of automatic approach and avoidance biases among children diagnosed with OCD. Design. Participants (N = 17) included children ages 8-16 who were enrolled in two larger intervention studies. Symptom severity was assessed via clinician, child, and parent ratings from the Children’s Yale Brown Obsessive Compulsive Scale. With the assistance of a clinician, parents and children worked collaboratively to identify threat pictures that triggered the child’s OCD obsessions and/or compulsions, as well as emotionally neutral pictures. These pictures were utilized in an Approach Avoidance Task (AAT). In this computerized task, children were presented with threat and neutral pictures on the screen one at a time, framed by a blue or green border. Participants were instructed to respond by pushing or pulling a joystick based on the color of the picture border, which resulted in the picture becoming progressively smaller (simulating avoidance) or larger (simulating approach), respectively. Reaction times were measured for each combination of stimulus type and response direction, thus allowing for calculation of bias scores for different stimulus-response combinations. Aim 1: To characterize the nature of approach-avoidance tendencies in children with OCD. Aim 2:To examine the relationship between approach-avoidance tendencies and OCD symptom severity. Results. All participants were able to identify an appropriate number of threat and neutral pictures for use in the task. Split-half reliability coefficients for individual reaction time measures were high, as were correlations between individual reaction time measures. When examining bias scores, reliability was acceptable only for approach bias (pull threat minus pull neutral). Participants were significantly faster to pull threat pictures toward themselves when compared to reaction times for pulling neutral pictures toward themselves (approach bias). Moreover, participants demonstrated a larger approach-avoidance bias (i.e., reaction time difference for pushing minus pulling pictures of a given stimulus type) for threat compared to neutral stimuli. Both of these effects were statistically significant in the opposite direction as hypothesized. Participants did not demonstrate a statistically significant avoidance bias (push threat minus push neutral). No correlations between bias scores and OCD symptom severity reached statistical significance. Conclusions. The current study demonstrates the feasibility of collecting idiographic stimuli from youth diagnosed with OCD, which had not yet been established in previous studies. Despite high reliability of individual reaction times, reliability of the bias scores may have been reduced by high correlations between individual reaction time means. Support for the hypothesized bias effects was limited. Establishing reliable measures of automatic approach and avoidance biases represents a critical area for continued research and a necessary step before firmer conclusions can be established about the nature of such biases or their relationship to symptoms.