A Practice Note discussing the test that the US Court of Appeals for the Federal Circuit and the Trademark Trial and Appeal Board (TTAB) apply when evaluating likelihood of confusion claims (also known as Lanham Act Section 2(d) claims) in inter partes proceedings and likelihood of confusion application refusals (also known as Lanham Act Section 2(d) refusals). This Note addresses each of the individual likelihood of confusion factors and the evidence and facts that weigh in favor of and against a likelihood of confusion finding.