Multi-tiered System of Supports/Response to Intervention (MTSS/RTI) is now mandated in a number of states, including Illinois, and being implemented at all grade levels. School social workers and school psychologists are typically involved in implementation; however, minimal information exists on the extent to which they collaborate. Results of an Illinois survey will be presented to provide a better understanding of the nature and degree of collaboration while identifying and analyzing student problems. Findings suggest that school social workers and school psychologists are engaging in collaboration at a relatively high rate and are mostly involved with tier 2 and tier 3 activities. Also, more than half of the respondents reported expanded leadership roles related to implementing MTSS/RTI, although obstacles to effective implementation included lack of time and training. Practice implications for the fields of school social work and school psychology will be discussed.