The aim of this work is to historically track and analyse the development and role of sound editing in Croatian cinema from the 1940s to the 1970s in the context of feature-length fiction films, in order to provide a detailed insight into the achievements and artistic practices of this important but often neglected film profession. To better understand the profession of sound editing and the context of its emergence, this work begins with a historical overview of the methods and practices of sound accompaniment in American cinema during the silent film era, followed by a comparative analysis of practices in Croatian cinema. Even during the silent film era, the use of speech, sound effects, and music, elements that would create soundscapes of future sound films, was notable. The first sound films were projected using various reproduction systems, but the system where both the visual and audio segment of the film were on a single filmstrip would ultimately prevail, laying the foundation for the development of the sound editing profession. Due to extremely limited technical and financial resources, Croatian cinema in the 1930s regularly produced only commissioned and promotional films in which the sound was shaped during synchronization. The beginnings of the sound editor profession in Croatia are closely tied to employment opportunities, greatly aided by the establishment of the first film companies and eventually the Jadran film studio, which resulted in the production of the first feature-length fiction film in 1944, marking the start of continuous film production. The first use of the title sound editor in the context of feature-length fiction films is documented in the credits of the film Zastava in 1949. Despite the establishment of technological conditions and the development of post-production systems and tools in Croatian cinema, a major challenge was the education of film professionals for working with sound film. Sound editors predominantly educated themselves for their profession through apprenticeship under more experienced colleagues and learned through practice, later supplemented by various workshops and courses. The practice of apprenticeship for work on early sound films was a dominant form of education in other countries as well. Education for film editors (both sound and picture) became institutionalized in 1969 with the founding of the Editing Department at the today’s Academy of Dramatic Art, University of Zagreb. The continuous production of feature-length fiction films, noticeable from the 1950s onwards, allowed for the tracking of the development of the sound editing profession. Over the coming years and through film soundscapes analysis, it becomes evident that editing techniques became more diverse with various distinct solutions adopted, specific editing methods became integrated into the soundscapes of future films, the dramaturgy of soundscapes became more complex, and the overall believability of the soundscapes was achieved not only occasionally but consistently throughout the entire film. A significant turning point in achieving synchronization, which is essential for creating convincing soundscapes, is represented by the film Tko pjeva zlo ne misli (1970), in which it is noticeable that all scenes were recorded with sound, unlike the previous practice where certain scenes (mostly shot outdoors) were recorded without sound. The end of the 1960s marked the attainment of a high standard in the sound editing profession (and picture editing profession as well), making it possible to establish the Editing Department at the former Academy of Theatre Arts, where practical artistic class teachings were led by experienced film professionals with extensive knowledge and experience, capable of educating the next generation of filmmakers. However, due to limited spatial, material, and performance capabilities, the Editing Department did not offer specialization in the field of sound editing, which was only made available to students with the launch of the graduate study program in Sound Design (in the academic year 2007/2008). The soundscapes of Croatian feature-length fiction films up to the 1970s were defined by only a few sound editors (Lidija Jojić, Tea Brunšmid, Živan Cvitković). They distinguished themselves through their work, innate affinities, and the determination and patience to find solutions and methods suitable for each film, thereby advancing their profession while maintaining professional standards. Their work, as well as the work of film picture editors, represents an unfairly neglected area of research, research in film studies, and expert theses, and this work aims to partially correct this omission.