Welcome to the home page of the workshop on Security Protocol Implementations: Development and Analysis (SPIDA). It will be held in London (United Kingdom), 23 April, 2018. The workshop will be organized in conjunction with IEEE EuroS&P 2018.Security protocols (such as TLS for internet, WPA2 for WiFi, GSM for mobile telephony, to mention just some of the broadly used ones) play a crucial role in protecting the digital communications and interactions we rely on in our modern society. The security of such protocols can break because of fundamental, inherent flaws, but the bulk of the security flaws are due to implementation flaws. The complexity and unclarity of typical protocol specifications makes it more likely to introduce such flaws and makes it harder to spot them. SPIDA seeks novel contributions and case studies that address the challenges when implementing security protocols. How can implementations be analysed, statically or dynamically, in a systematic way? How can we make sure that the specifications are precise, but still easy to understand and implement correctly? And how to assure implementations faithfully follow such specifications?