This two-study research built and validated the new questionnaire "LO-COMPASS: Learning Orientation-Cognition Metacognition Participation Assessment" aimed at capturing the interplay between cognitive, metacognitive, and affective-motivational learning attributes in middle school students' learning orientations proved to be significant predictors of middle school students' achievements. In Study 1: (N = 212) an Exploratory Factorial Analysis (EFA) was carried out to investigate the factorial latent structure of the questionnaire, while in Study 2: (N = 233) this structure was checked by a Confirmatory Factorial Analysis (CFA). The goodness of fit indices resulting from the CFA were sufficiently good overall: CFI = 0.89, TLI = 0.92, RMSEA = 0.04, SRMR = 0.06. Furthermore, in Study 2 the convergent/discriminant validity of the latent factors of the questionnaire and their association with school achievement were verified. LO-COMPASS factors including an interplay of cognitive, metacognitive, and affective-motivational attributes of learning orientations are discussed within the framework of the existing literature and the practical implications are delineated.