The present study investigated the association between Korean speech proficiency and school adaptation of the returnees from abroad. It also explored the issues of their Korean speech performance and suggested appropriate plans for educating them to improve the speech proficiency. The study graded their Korean competence into four levels - maintenance level (type 1), loss of Korean for learning (type 2), loss of Korean for living (type 3) and basic Korean level (type 4). It investigated the school adaptation and Korean speaking-listening competence for the four levels. Analyzing the speech performance of the returnees exhibited immaturities in debate skill, formal speech skill, general speech skill, expression of their thinking, awkward non-verbal or para-language expression and loss of self-confidence. Therefore, the speech education for the returnees must check the loss of learning of the discourse type in terms of education by level and provide supplementary education in order to reach the goal of improving speech capability. Besides, it also needs to restructure the contents and sequence of the curriculum for speech communication.