Reading motivation is multidimensional and a critical contributor to students' reading comprehension skill. Its multidimensionality is problematic, as there is currently no consensus on the dimensions underlying reading motivation, which are being tested through a variety of instruments that lack statistical validation. Our goal was to discuss the structure, reliability, and validity of a reading motivation scale in relation to prior theoretical proposals. The scale considered four affirming and four undermining reading motivations and was tested with 172 students from 2nd to 6th grade. Its structure was assessed using CFA and EFA. A four-factor structure had the best fit for the data: (1) Reading value and intrinsic motivation; (2) reading devalue and avoidance; (3) perceived self-efficacy; and (4) perceived difficulty. The results supported some prior theoretical distinctions, but question the appropriateness of widely used scales and suggest the need for more research on the multidimensionality of reading motivation.