後期中等教育乃是學制中從不分化邁向分化的重要階段，而試探乃是此一教育階段的重要功能之一。本文首先檢視後期中等教育的功能，繼之分析後期中等教育課程的分化與試探，並詳細探討我國後中各類課程之試探特色與限制。基於上述分析，本文主張：試探是後期中等教育階段不可或缺的教育功能，而試探功能的發揮，則有賴四個重要原則之落實，最後並據此提出四項建議：後期中等教育應避免過早分化，限制學生的試探機會；應強調一般科目的學習，重視廣泛學習的機會；課程架構應具漸進分化的精神，藉由試探歷程，逐步引導學生進入專精學習；課程彈性有助於因應不同學生之需要，但仍需妥善運用，以彰顯試探功能之發揮。

Upper secondary education is a key stage in which more differentiation is introduced and in which education is gradually transformed as post-compulsory. The stage is therefore important for students to move towards advanced education or training and for a school system to enact educational selection. However, it is commonly showed by the research evidence available, that many high school students and university students in Taiwan are still uncertain about their possible career and future development. This paper focuses on educational differentiation and exploration in upper secondary education and, in particular, investigates the exploratory role of the upper secondary curriculum. The research method adopted is mainly documentary analysis. According to the four principles of the curriculum highlighted in this paper, three main pathways of upper secondary education in Taiwan with their curriculum are analyzed and discussed. They are senior high schools of general pathway, vocational high schools of vocational pathways, and comprehensive high schools with features of the two pathways. Based on the investigation in this paper, it is argued that educational exploration is one of the four key roles of upper secondary education. To fulfill the exploratory role, it is important to emphasize four principles including last differentiation, broad learning, progressive specialization, and curriculum flexibility. Finally, four recommendations are suggested.