The current study examined factors associated with adolescent and parent participation in a coping skills intervention for adolescent girls with inflammatory bowel disease (IBD) and examined factors associated with attrition related to intermittent missing data. Thirty-one adolescent girls with IBD and their parents enrolled in the intervention. Psychosocial and disease factors related to participation in the 6-week web component of the coping skills intervention were examined as were baseline group differences between those who provided post-treatment data and those who did not. Adolescents experiencing more difficulties related to their disease and psychosocial functioning participated less in the web component of the treatment intervention. Families who attrited had higher baseline levels of parental catastrophic thoughts, parenting stress, and adolescent depression. Families experiencing greater levels of psychological and disease-related difficulties may be at risk for low participation and eventual dropout from pediatric IBD psychological treatment interventions.