The research showed that probation officers were more likely than clinicians to assess an offender as having made progress in treatment. Clinicians had a greater tendency to indicate progress that was driven by their perceptions of offenders of psychological insight. When probation officers perceived progress, it was driven by their perception of self-labeling by offenders. Co-facilitators did not necessarily have to agree in their perceptions of treatment progress, but should be able to communicate their perceptions to their co-facilitator and be willing to work together to devise the best plan for the continued management of the offender. Co-facilitation is similar to a team teaching approach where the curriculum and structure of the group treatment are administered and monitored by one probation officer and one clinician. This research study examined how probation officers and clinicians assigned to co-facilitate sex offender treatment groups assessed treatment progress. Data were collected from the progress assessments of 144 sex offenders assigned to treatment as a condition of their probation. Probation officers' and clinicians' perceptions were measured against the behavioral factors of compliance with probation conditions, psychological insight, and labeling self as a sex offender. Tables, figures, appendixes, notes, and references