In recent years, Heritage Language Programs have been attracting more and more attention in the European academic and educational policy contexts. In Germany, many efforts are being undertaken to foster the teaching of heritage languages in schools. This paper provides an overview of the teaching of Spanish as a Heritage Language in Germany through the long-established Program 'Spanish Culture and Language Lessons' ("Aulas de Lengua y Cultura Españolas") funded by the Spanish Ministry of Education for school-aged Spanish heritage speakers. The principal objectives of the study are to analyze the main fostering and constraining factors to participate in this program and to propose improvement measures. To achieve these purposes, a mixed quantitative and qualitative research methodology has been used. The findings are discussed according to these main topics arising during the research process: reasons for students to participate and learning needs, teaching challenges, family implication, relationship with the regular formal education system, blended learning, linguistic and culture diversity. Moreover, improvement measures for this Spanish Heritage Language program are suggested. The main conclusions may be useful for heritage language teachers and program managers in other heritage language (HL) programs in Germany and more generally in Europe.