Current theories concerning the comprehension of noun-noun combinations propose that relational interpretations are the result of tlie modifier filling some role within the head noun (Murphy. 1988; Wisniewski, 1997), whereas property interpretations involve the structural alignment of the head noun and modifier concepts (Wisniewski, 1997). In this paper we argue that structural alignment underlies the formation of both relational and property interpretations of noun-noun combinations. Property interpretations result from the alignment of the modifier with the head noun, whereas relational interpretations result from the alignment of the modifier with a filler in the head noun. Modifiers for noun-noun combinations were chosen based on their similarity to relational fillers in the head noun concept. Results indicated that frequency of instantiation of relational interpretations was positively correlated with the similarity of the modifier to fillers in the head noun. Similarity of modifier to fillers in the head noun predicted frequency of instantiation of relational interpretations to a greater degree than the rated ability of modifiers to fill roles in the head noun concept.