Abstract The present study investigates the syntactic derivation of por que (‘why’) in Brazilian Portuguese (BP). The syntactic properties of why and its counterparts across languages have long been a fruitful area of inquiry in theoretical syntax. Bonan and Shlonsky (2021) , for instance, examine the distinct behaviors of parché and parcossa in Trevisan, arguing for two distinct external merge positions. In BP, por que can appear in at least three different syntactic positions without altering its interpretation. Drawing on previous literature on why counterparts and employing precedence and transitivity tests involving negation and adverbial elements, we argue that a unified syntactic position for BP por que is viable — specifically, Spec,ReasonP in the left periphery. This analysis aligns with previous cartographic research that classifies reason wh-phrases as high adverbs across languages ( Rizzi, 2001 ; Shlonsky & Soare, 2011 ; Shlonsky & Bonan; Tsai, 2008, among others).