In national contexts where curriculum policies explicitly advocate for the development of students’ higher order thinking capabilities, evidence suggests that achieving this goal can be quite elusive. In this article we explore this challenge by drawing on senior secondary school examples from two national contexts (New Zealand and Israel) that demonstrate how the implementation of student-centred pedagogies can lead to the development of fragmented, shallow knowledge rather than the deep, connected knowledge envisaged by the actual policies. Dilemmas common to both nations include: a lack of understanding that inquiry learning should include an epistemic focus; concerns about how to balance breadth and depth of students’ learning; and a lack of strong models for rethinking purposes for teaching and for assessing the types of learning outcomes envisaged by the curriculum innovations. We contend that the challenges we describe stem at least partially from a tight–loose dilemma common to both countries. In the contexts we discuss, looseness is associated with a lack of clear epistemic criteria for teaching, assessing, and designing interventions. We suggest that, in order to improve the implementation of innovative forms of learning and instruction, issues pertaining to epistemic criteria must be tightened.