According to the guideline of the curriculum stipulated in the Courses of Study (gakushuushidouryoyou), science education in Japan has been addressed to strengthen problem-based learning. Since 2000, the development of children’s ability to live based on problem-solving abilities has become a pillar of the Courses of Study. To nurture this ability, a new period for integrated study (PIS) or in Japanese called shougoutekina gakushuu jikan has been created. Under a specific theme, PIS activities were formulated on acquiring cross-curricular knowledge or interdisciplinary concepts, cooperation, and the development of children’s problem-solving ability processes. This chapter outlines the concepts, principles, and practices of PIS in the Japanese education system; the framework of children’s abilities to be raised; and the prospects of the new Courses of Study.