Women are underrepresented in Informatics (Computer Science, Computer Engineering, Computing, ICT) at all levels, from undergraduate and graduate studies to participation and leadership in academia and industry. Increasing female representation in the field is a grand challenge for academics, policymakers, and society as a whole. Although the problem is evident, progress has been invariably slow, in spite of all the momentum and impulse for change happening across Europe. The main aim of this COST Action is to improve gender balance in Informatics through the creation and strengthening of a truly multi-cultural European network of academics working on the forefront of the efforts in their countries, institutions and research communities. We will be building on their knowledge, experiences, struggles, successes, and failures, learning and sharing what has worked and how it could be transferred to other institutions and countries. Among other outcomes, the Action will provide the academic community, policymakers, industry and other stakeholders with recommendations and guidelines to address the following key challenges: (i) How to have more girls choosing Informatics as their higher education studies and profession; (ii) How to retain female students and assure they finish their studies and start successful careers in the field; (iii) How to encourage more female Ph.D. and postdoctoral researchers to remain in the academic career and apply for professorships in Informatics departments; (iv) How to support and inspire young women in their careers and help them to overcome the main hurdles that prevent women to reach senior positions.