There is widespread support for expanding apprenticeships in the United States, but employer participation remains stubbornly low, especially in industries where apprenticeships are uncommon. This isn’t for lack of trying; intermediaries and technical assistance providers have developed workarounds, states and the federal government have launched initiatives and grants, and funders have supported pilot programs and communities of practice. But it’s not enough. Our research, including interviews with 14 experts and nine employers, suggests that minor tweaks to the U.S. apprenticeship system won’t be sufficient to scale it across many industries and occupations.