Iberian Strings 2019 is the tenth annual meeting of the Spanish and Portuguese string theory community, where recent developments in the field of supergravity, strings, branes and gauge theory are discussed. String theorists from outside the Iberian Peninsula are welcome to participate in the meeting. Previous Iberian Strings Meetings were held in Granada (2018), Lisbon (2017), Madrid (2016), Salamanca (2015), Palencia (2014), Lisbon (2013), Bilbao (2012), Valencia (2011) and Oporto (2010). This conference series followed up on the "Workshop on Gravitational Aspects of Strings and Branes" and the "Northwest Strings" that Iberian String theorists had been organizing since the early 2000s. In this edition we will have plenary lectures by: Mariana Graña (IPhT, Saclay) Diego Hofman (Amsterdam U) Kyriakos Papadodimas (ICTP, Trieste) Linus Wulff (Masaryk U., Brno) In addition, there will be contributed talks by participants. There will be a conference dinner at Can Cortada on Thursday January 24th at 20:00h. Scientific Advisory Committee: Igor Bandos (UPV-EHU, Bilbao) Miguel Costa (Porto U.) José Luis Fernández Barbón (IFT, Madrid) Rafael Hernández (U. C. Madrid) Bert Janssen (U. Granada) María Antonia Lledó (U. Valencia) Gabriel Lopes Cardoso (IST Lisbon) Yolanda Lozano (U. Oviedo) Javier Mas (U. Santiago de Compostela) Tomás Ortín (IFT, Madrid) Miguel Ángel Vázquez Mozo (U. Salamanca) Local Organizing Committee: Roberto Emparan (co-chair) David Mateos (co-chair) Tomeu Fiol Tomás Andrade Yago Bea Antón Fernández Faedo Antonia Micol Frassino Aron Jansen Jorge Rocha Jakob Salzer Ryotaku Suzuki