本研究之目的乃透過家庭中的手足遊戲情境，探究排行老二之幼兒分別與其年長手足或年幼手足，及同時與其年長、年幼手足的遊戲互動。研究者以質性研究之方式進行，進入一育有三子之家庭中，以排行老二之幼兒為研究對象，進行為期六個月之觀察與非正式訪談。研究結果從排行老二之幼兒的角度說明該幼兒分別與年長手足或年幼手足，以及同時與年長及年幼手足之遊戲類型、遊戲互動行為，包括遊戲開啟的方式、遊戲進行中之特色、結束遊戲的方式，以及三人間的手足關係，並討論排行老二之幼兒在遊戲中顯現的特色與優勢。

The purpose of the research is to study play interaction of the second born child with his elder and younger sibling respectively, to study the interaction among all siblings playing together，and to analyze sibling relationship further. The research is based on the family with three children and an observation on the second born child for six months in a qualitative research method. The findings include three parts, which are the onset of play, the traits in the progress of play, and the end of play interaction of the second born child with his siblings.Finally, the study also finds that the second born child's benefits from sibling interaction in play include: trying out various strategies, perseverance, training in social skills, and shifting in multiple roles.