Based on the relationship between Systemic Functional Linguistics (SFL) and translation, and with the aim of resolving the existing dispute over the subjective and unjustified evaluation of translation quality, this study provides an objective approach to the quality assessment of English into Arabic translation. This study uses the interpersonal metafunction of language to assess the quality of the translation. The assessment goal is to check if the interpersonal metafunction of the translated text is equivalent to the interpersonal metafunction of the original text. The tools derived from Halliday's SFL are important in the analysis because SFL is the linguistic branch that deals closely with language functions and social aspects. At the same time, the translation is seen as a whole product as well as a series of processes (Bardi, 2008). The study adopts a descriptive contrastive approach to present the main choices of interpersonal metafunction systems and their realizations in English and Arabic and uses SFL to analyze grammatical realizations of Mood system choices, seeking the Tenor variable of texts represented in context. The objective assessment is based on giving a score for each time there is a success in finding the appropriate equivalent. The texts used are originally published texts in English and their authenticated published translations in Arabic. The texts are taken from single registers, and the analysis was limited to simple clauses.