Maybe someone can help with this one – probably published in 1950s or early 60s, but I read it in the 70s. No dust jacket, since I think my mom got it at a library or garage sale – but hardback, plain red cover. Girl (named Gabrielle, I think, perhaps French-Canadian?) in high school, trying to fit in. I remember she starts writing anonymous reports to the school paper with the pen name “Gadfly.” At some point she wants to get a job and hears the local department store wants girls to model clothing – she doesn’t have anything fancy, but shows up in her snowsuit and at the audition poses as if she’s skiing – and gets the job. At some point she goes to a barn dance or hayride and meets a college boy, which impresses her peers. I thought the name of the book was something like “Gabby” but that doesn’t seem to turn anything up.
Lost Classics of Teen Lit: Name That Book! 