Background: Residential drug rehabilitation is often seen as a treatment of last resort for people with severe substance abuse issues. These clients present with more severe symptoms, and frequent psychiatric comorbidities relative to outpatients. Given the complex nature of this client group, a high proportion of clients seeking treatment often do not enter treatment, and of those who do, many exit prematurely. Given the highly social nature of residential drug rehabilitation services, it has been argued that social anxieties might decrease the likelihood of an individual entering treatment, or increase the likelihood of them prematurely exiting treatment. The current paper reports on the protocol of a Randomised Control Trial which examined whether treatment of social anxiety prior to entry to treatment improves entry rates and retention in residential drug rehabilitation.Method/design: A Randomised Control Trial comparing a social skills treatment with a treatment as usual control group was employed. The social skills training program was based on the principles of Cognitive Behaviour Therapy, and was adapted from Ron Rapee's social skills training program. A permutated block randomisation procedure was utilised. Participants are followed up at the completion of the program (or baseline plus six weeks for controls) and at three months following entry into residential rehabilitation (or six months post-baseline for participants who do not enter treatment).Discussion: The current study could potentially have implications for addressing social anxiety within residential drug treatment services in order to improve entry and retention in treatment. The results might suggest that the use of additional screening tools in intake assessments, a focus on coping with social anxieties in support groups for clients waiting to enter treatment, and greater awareness of social anxiety issues is warranted.Australian New Zealand clinical trials registry: Australian New Zealand Clinical Trials Registry (ACTRN) registration number: ACTRN12611000579998.