One of the critical components of any intervention model in special education is the concept of increasingly intensive interventions (iii).  As students with disabilities are screened and placed into the appropriate research-based program of instruction, they are progress monitored to determine the effectiveness of the instruction and of the supplementary aids and services.  Formative assessment, or progress monitoring, asks the question “Is the student learning what the teacher is teaching?”  If through progress monitoring it is determined that the instruction is not meeting the needs of the student in that the student is not positively responding to instruction, a continuum of increasingly intensive strategies, supplements and interventions must be made available to the teacher as they modify instruction to improve the student’s learning.  These articles are part of the research-base for the continuum of increasingly intensive research-based strategies, supplements, interventions and progress monitoring systems currently in use through the Office of Specialized Services (OSS).