This chapter analyzes Ruth Garrett Millikan’s teleosemantic theory of mental representation, focusing on her innovative producer–consumer model and etiological concept of proper function. Through examination of her biosemantics framework, it demonstrates how proper functions arise from selective history and how the producer–consumer system enables both social and individual representations. The analysis reveals how Millikan’s approach naturalizes intentionality while addressing key challenges in theories of mental content. The discussion evaluates Millikan’s treatment of representational error as dysfunction, showing how her framework handles misrepresentation through historical proper functions rather than current causal relations. While successfully accounting for the possibility of error, the chapter demonstrates that Millikan’s theory faces challenges regarding system-detectable error and risks trivializing the concept of representation by including simple sensory registrations. Through detailed examination of examples like the bee dance and frog predation, the chapter establishes that although Millikan’s framework provides sophisticated tools for understanding representational content and error, it ultimately falls short of explaining how cognitive systems detect their own errors. This critique sets up subsequent exploration of alternative approaches to mental representation that better account for system-detectable error.