Translanguaging has attracted growing attention in foreign language education; however, despite generally positive student and teacher attitudes, empirical evidence remains limited, particularly in third language (L3) learning. Addressing this gap, the present study examines how translanguaging pedagogy supports multilingual development by investigating additional language developers' L3 German spoken skills development and perceptions of translanguaging classroom practices. Grounded in translanguaging theory and complexity theory, the study adopts a mixed-methods design. Ninety-nine high school students participated in a nine-week A1-level spoken German course. Participants were assigned to a monolingual German-only condition or to bilingual (Turkish - German) and trilingual (Turkish - German - English) translanguaging conditions. Quantitative data were analyzed using ANOVA, while qualitative data were thematically analyzed. Results indicate significantly greater gains in L3 German spoken skills for learners in translanguaging conditions, with the trilingual group demonstrating the strongest improvement. Qualitative findings reveal that the bilingual group primarily exhibited cognitive and affective development in contrast to monolingual group reporting minimal strategic reflection, ongoing uncertainty, and affective barriers. The trilingual group showed more explicit, systematic, and strategic meta-level reflections. Implications are discussed.