This study aims to portray the conditions for the transposition of EU standards into the internal security of applicant states, with a focus on Turkey. The analysis evaluates the conditions that determine the EU’s success in effecting changes in the internal security of Turkey.Campaigns against organised crime, terrorism and drugs were selected as case studies to make an assessment of different policy domains under Justice and Home Affairs (JHA). In doing so, this study aims to explore how the EU operates the external dimension of JHA in applicant states, and under which conditions the EU is able to ensure alignment with JHA.Numerous interviews were conducted with officials at security institutions and public agencies in Turkey as well as in the EU as part of the analysis. Legislation, government decisions, internal training documents, strategy papers and security assessment reports were also reviewed to uncover the influence of the EU on Turkey.This book will add value to studies undertaken in academia focusing on EU-Turkey relations, JHA and the fight against transnational crime.