The intention of this paper is to contribute to refining Appraisal theory, which hasrecently emerged from research within Systemic Functional Linguistics (SFL). Appraisalis basically concerned with a writer's use of evaluative language. The specificaspect under investigation is the delineation of multiple coding in analysing one ofthe appraisal systems referred to as ATTITUDE. This paper proposes the concept ofmultiple coding consisting of multi-layering and double coding for the analysis ofATTITUDE. Analyses of argumentative essays written by undergraduate universitystudents revealed that multiple coding was useful in identifying the differences betweenhigh-graded essays (HGEs) and low-graded essays (LGEs). Multi-layering anddouble coding of ATTITUDE occurred much more frequently in the analyses of theHGEs than LGEs.