The right to contest automated decisions as provided by Article 22 of the General Data Protection Regulation (GDPR) is a due process provision with concrete transparency implications. Based on this, the paper in hand aims, first, to provide an interpretation of Art 22 and the right to contest (as the key provision in determining the contours of transparency in relation to automated decisions under the GDPR); second, to provide a systematic account of possible administrative, procedural, and technical mechanisms (transparency measures) that could be deployed for the purpose contesting automated decisions; and third, to examine the compatibility of these mechanisms with the GDPR. Following the introduction, Part II starts with an analysis of the newly enacted right to contest solely automated decisions as provided under Article 22 of the GDPR. This part identifies the right to contest in Article 22 as the core remedy, with inherent transparency requirements which are foundational for due process. Setting the right to contest as the backbone of protection against the adverse effects of solely automated decisions, Part III focuses on certain key points and provisions under the GDPR, which are described as the 1st layer (humanintelligible) transparency. This part explores to what extent "information and access" rights (Articles 13, 14, and 15) could satisfy the transparency requirements for the purposes of contestation as explained in Part II. Next, Part IV briefly identifies the limits of 1st layer transparencyexplaining how technical complexity together with competition and integrity-related concerns render human-level transparency either infeasible or legally impossible. In what follows, Part V conceptualizes a 2nd layer of transparency which consists of further administrative, procedural, and technical measures (i.e., design choices facilitating interpretability, institutional oversight, and algorithmic scrutiny). Finally, Part VI identifies four regulatory options, combining 1st and 2nd layer transparency measures to implement Article 22. The primary aim of the paper is to provide a systematic interpretation of Article 22 and examine how "the right to contest solely automated decisions" could help give meaning to the overall transparency provisions of the GDPR. With a view to transcend the current debates about the existence of a so-called right to an explanation, the paper develops an interdisciplinary approach, focusing on the specific transparency implications of the "right to contest" as a remedy of procedural nature.