Three reference standards (RS) can be used when evaluating academic achievement: individual reference standard (IRS), social reference standard (SRS), and criterion reference standard (CRS). The aim of the present study of 410 fourth graders was (1) to conceptualize the three RS by factor analyses, (2) assess the prediction of math self-concept (MSC) and math grades (MG) by the three RS, and (3) reveal mediating effects of MSC and interaction effects of SRS on individual-And class level (SRSC) as well as class-Average achievement (CA). Factor analyses showed that a three factor-model fi ts best to the data. Positive relations were found between all constructs and MG. Multilevel analysis yielded positive effects of IRS and CRS on MSC, MSC on MG as well as SRS on MG, while there were negative effects of SRSC and CA on MG.