Secure digital infrastructures form the backbone of any modern, industrialised society and economy, and have been the drivers of policy and legislative developments in Australia and other countries worldwide. Australia launched several initiatives to bolster its digital security and resilience, including the 2023–2030 Australian Cyber Security Strategy and Action Plan. The concept of resilience plays a crucial role in critical infrastructure protection in Australia. Security and resilience work together in a critical infrastructure setting. This chapter outlines the legal framework that underpins the security of critical infrastructure in Australia by exploring the operative provisions of the Security of Critical Infrastructure Act 2018 (Cth). The chapter considers the complex interplay between regulation, resilience, and security, noting some of the challenges and opportunities of this crucial relationship.