Exposure-based cognitive-behavioral therapy (i.e., "exposure therapy"), which entails repeated and prolonged confrontation with feared situations/stimuli, is the most effective treatment for anxiety disorders (e.g., arachnophobia). Safety behaviors are actions performed to prevent, minimize, or escape a feared catastrophe and/or associated distress (e.g., wearing thick shoes or gloves when around areas where there might be spiders). It is understood that safety behaviors contribute to the development and maintenance of anxiety disorders; accordingly, patients' safety behaviors are traditionally eliminated as soon as possible during exposure therapy (i.e., "response prevention"). Unfortunately, not everyone who receives exposure therapy benefits from this approach. To address the limitations of exposure's effectiveness, some experts have questioned the clinical convention of response prevention during exposure therapy. Specifically, they propose the "judicious use of safety behaviors": the careful and strategic incorporation of safety behaviors during exposure therapy. The controversial role of permitting safety behaviors during exposure has garnered substantial research attention, yet study findings are mixed. The current study, therefore, was designed to improve upon the methodological limitations of previous related research and examine the relative efficacy of traditional exposure with response prevention (E/RP) and the experimental exposure with the judicious use of safety behaviors (E/JU) in a sample of adults with arachnophobia. In light of previous related research, several hypotheses were made regarding the short- (posttreatment) and long-term (1-month follow-up) treatment effects:

1. Primary outcomes: E/RP participants will demonstrate greater improvement in spider phobia than the E/JU participants along behavioral and self-report symptom measures at follow-up.
2. Secondary outcomes: Treatment acceptability and tolerability will be higher for E/JU participants, relative to E/RP participants, before beginning exposures and at posttreatment, but not at follow-up. In addition, hypothesize that E/RP participants will report greater reductions in peak distress and greater improvements in distress tolerance relative to E/JU participants at follow-up.
3. Additional outcome: Exploratory analyses will be conducted to compare the relative rate of behavioral approach and exposure goal completion between treatment conditions.

Inclusion Criteria:

• Being at least 18 years old
• Presence of clinically significant spider phobia
• English fluency
• Willingness to attend and audiotape all study sessions

Exclusion Criteria:

• Spider or bee allergies
• Previous trial of exposure-based cognitive-behavioral therapy for any anxiety problem
• Current alcohol or substance use disorder
• Lifetime symptoms of mania or psychosis
• Voluntarily report current suicidal ideation
• Complete 10 or more steps on the behavioral approach task administered at the pre-treatment assessment

Individuals may contact the primary investigator (Shannon M. Blakey) to request access to the Individual Patient Data (IPD) after the termination of the study and publication of the primary outcomes manuscript.

Pre-determined condition allocation was listed in an Excel spreadsheet and concealed with black cell masking color. Interested individuals who met initial eligibility criteria during a pre-enrollment phone screening were entered in the order of screening in the assignment Excel spreadsheet (that was already masked to conceal condition assignment). Only the participant's therapist viewed the allocated condition immediately prior to the first treatment session by temporarily lifting the cell mask.