The theme selected for the 2019 EuroCALL conference held in Louvain-la-Neuve was ‘CALL and complexity’. As languages are known to be intrinsically and linguistically complex, as are the many determinants of learning (additional) languages, complexity is viewed as a challenge to be embraced collectively. The 2019 conference allowed us to pay tribute to providers of CALL solutions and to recognize ... [Show full abstract] the complexity of their task. We hope you will enjoy reading this volume as it offers a rich glimpse into the numerous debates that took place during EuroCALL 2019. We look forward to continuing those debates and discussions with you at the next EuroCALL conferences!