The Erasmus+ program (2014–2020) is one of the main initiatives developed by the European Commission in the field of education and is the final joint evolution of other minor and prior actions that provide schools and teachers with funding to carry out international mobility projects with a variety of formative activities. The benefits of carrying out international mobility activities to strengthen student learning and teacher training are well known and have been researched or reported even from the early stages of a program that was born back in the 1980s but has always been focused on the university level. When considering teachers at early levels (schools and high schools), the 2014–2020 Erasmus+ program was the main source of funding to grant Spanish teachers permanent training activities abroad with a direct positive impact on their careers. The year 2020 is the last year of the first evolution of the Erasmus+ program, which has been renewed, extended, and strengthened for a new six-year term (2021–2027). However, 2020 has also been a significant year. The COVID-19 global pandemic continues to affect the mobility of citizens within the different territories of the union and, thus, have a direct negative impact on international teacher and student mobility. Being 2020 the end of a cycle and a critical moment, it is the perfect time to conduct an analysis of the data associated with the participation of teachers and schools in Spain, their perceptions of the program, the different activities carried out, and the impact of the pandemic. This research study is based on an analysis of an opinion survey through a nationwide sample of teachers participating in KA101 Erasmus+ projects. This paper gathers and presents data and conclusions using information previously not available that most of the time is published in official reports globally without considering the particularities of the different states of the European Union.