Girls and young women have become more ubiquitous than ever in twenty-first century media culture. This is particularly true of cinema, as some of the most successful recent films are centred around young female protagonists, such as The Hunger Games franchise (Ross, 2012) and Fifty Shades of Grey (Taylor-Johnson, 2015). British cinema has also witnessed a proportionate increase in girl-centred films since the millennium, some of which are contemporary British cinema’s most successful films. This includes commercial hits such as StreetDance 3D (Giwa and Pasquini, 2010) and St Trinian’s (Parker and Thompson, 2007), as well as an increasing number of critically acclaimed films by female filmmakers, such as Fish Tank (Arnold, 2009) and The Falling (Morley, 2014). However, these films have so far received little or no academic attention. This thesis explores how young femininity is constructed in female-centred British films between 2000 and 2015 in an era defined as postfeminist. It examines key themes such as girls’ ambitions, education and friendship. I use a combination of textual analysis and critical reception study, as well as analysis of extra-textual and paratextual materials where appropriate, to examine how discourses of girlhood are mediated both within the films themselves and outside of them in order to discern how these films and their critical reception contribute to, and are informed by, ideas about girlhood that circulate within the wider culture. In doing so, I argue for a nationally-specific postfeminist framework, and consequently provide a greater understanding of how postfeminism is articulated within a British context. I also seek to counter the author-led, masculine bias within British cinema through positioning critically respected films alongside critically maligned films, particularly those aimed at young girls, in order to provide these films with much-needed academic attention and demonstrate that they are worthy of consideration in relation to British cinema’s output in the twenty first century.