The Gatsby "Good Practical Science" report (Gatsby, 2017) identified opportunities to carry out open-ended investigative projects as one of ten benchmarks for good practical science. However, there is currently no requirement for post-16 students in England to have access to such opportunities as this is not required by A-level specifications (the most common post-16 qualification in England). Nevertheless, some teachers incorporate open-ended investigative work into post-16 teaching. Drawing on in-depth semi-structured interviews with 12 teachers, enablers of and barriers to open-ended investigation are identified, and the ways in which several teachers have successfully implemented such work are demonstrated through vignettes. Ways that teachers can use and value open-ended project work within current A-level specifications are presented.