Trousers suit, pantsuit—where did one leave off, and the other begin? Women wore trousers in the nineteenth century in special circumstances. For one example, the famous animal painter Rosa Bonheur wore pants for outdoor painting expeditions. But such clothing wasn’t acceptable for street wear. The early twentieth century couturiers started a trend for feminine slacks, limiting them for specific leisure occasions, such as beach wear or garden parties. We find illustrations of these outfits by the 1920s, with variations intermittently through the 30s and 40s. Actresses like Hepburn and Dietrich helped, but didn’t cinch the deal for social acceptance. Which brings us to the 1960s. I think that we can look at pop culture, particularly rock n’ roll, for the genesis of feminine pants acceptance. The long Summer of Love that was the late 60s saw the advent of the unisex look, expressed best in the wearing of denim jeans. This was also the period in which militant feminism was born. The time was one of general disaffection with many things in society, and women were able to don pants as part of this protest. The men and women that led popular music in that period played an essential role in getting everyone accustomed to the sight of women in pants. Designer Tommy Hilfiger thinks so too, and you can see his endorsement of my theory in words and pictures if you peruse his Rock style: how fashion moves to music.