What should assessment and instruction for students whose level of support rises to the pinnacle of the MTSS triangle be composed of? This chapter, rooted in the practices of the United States, will review a multi-tiered system of support and then discuss the dual identification of multilingual learners (MLs) needing both language acquisition support and special education services for a learning disability or cognitive impairment. Since these students require a high degree of specialization, we will also examine the roles that various individuals play in the identification, instruction, and support of these dually identified students. The chapter will then conclude with a discussion of access and comprehensibility of the content through the use of differentiation, scaffolding, accommodations, and modifications that aim to assist students in overcoming both linguistic and cognitive barriers in order to find success in the general education setting.