Treatment for trichotillomania is notably limited, preventing suffering individuals from having access to treatment. To address this need, researchers have developed and tested asynchronous online interventions for adults with trichotillomania. A factor that may impact the efficacy of these programs is the use of phone check-ins (or similar coaching support) to improve treatment adherence in website treatment delivery. In the current study we evaluated the role of check-ins on treatment adherence and efficacy of a website delivering acceptance and commitment therapy-enhanced behavior therapy (A-EBT). A sample of 101 adults with trichotillomania were randomly assigned to an A-EBT web-based intervention with or without phone check-in support. Adherence to the web-based program was not significantly improved by check-ins and treatment outcomes did not vary by condition (with or without check-ins). However, adherence to the program across conditions, did predict treatment outcomes. The program was found to be effective at decreasing trichotillomania symptom severity and improving trichotillomania specific psychological inflexibility over time across check-in conditions. Our findings suggest that check-ins did not improve adherence to or efficacy of the program, thus supporting recent literature suggesting that check-ins do not necessarily improve program adherence.