Abstract: This essay discusses how several institutions might be designed to implement popular constitutionalism within a liberal constitutionalism frame. The institutions are (1) forms of direct popular legislation such as referendums, (2) imperative mandates or instructions to representatives that the representatives must follow, sanctioned by automatically removing a noncompliant representative from office, and (3) modern communications technologies used to elicit citizen views as an alternative to voting (or polling). As to referendums, it critiques arguments (1) that referendums can oversimplify complex policy options in ways that sometimes produce outcomes that are indefensible in principle, incoherent, and inconsistent with what the people would prefer after the kind of deliberation that occurs in representative assemblies, and (2) that referendums systematically, though not inevitably, threaten rights of minorities that liberal constitutionalism guarantees. As to imperative mandates, it argues that objections track those to referendums, and offers parallel responses. And as to modern communications technologies, it focuses on such concerns that they fail to take advantage of specialized knowledge, and argues that overestimate the degree to which specialists actually have specialized knowledge and underestimate the degree to which such knowledge is available within a population of ordinary people and observes that sometimes domains in which specialized knowledge really is required can be identified in advance and exempted from these mechanisms.