On 16 December 2019, Directive (EU) 2019/1937 of the European Parliament and of the Council of 23 October 2019 on the protection of persons who report breaches of Union law entered into force (hereinafter: Whistleblower Directive; WBD). Based on a Commission proposal of 23 April 2018 and accompanied by an intensive policy debate, the final version of the Directive represents the most far-reaching piece of European Union legislation in the field of whistleblowing law to date, both in terms of depth and scope of regulation. The Member States of the European Union are now obliged to transpose the Directive’s provisions essentially by 17 December 2021. For most Member States, this will mark the first time they will adopt a comprehensive whistleblowing law. Hence, the transposition of the WBD will bring with it various challenges, but also multiple opportunities to improve the current legal framework and its practical implications, both of which are discussed in this two-part article series. Part 1 of the series will first discuss the Directive’s background and the main regulatory elements, followed by an in-depth analysis of its material and personal scope as well as the general conditions for whistleblower protection.