At the time of the Revolution, many women did not observe hijab, so when the hijab dress code became compulsory a couple of years after the victory of the Islamic Revolution, a new type of hijab was introduced and took its place along the chador. This took the shape and the name of manteau, a loose overcoat worn over top and slacks, or mid-calf skirt with thick hosiery and a headscarf. Women who didn’t want to wear a chador could wear a manteau and a headscarf.
At first some thought that women who did not observe hijab wore a manteau and that the really pious ones wore a chador, but this belief has changed over the years, with many pious women wearing manteaus rather than chadors, or others wearing a chador because of work requirements (e.g. in some governmental agencies and in some universities) rather than by personal conviction. A wide variety of manteau styles have developed: casual (for leisure occasions), official (for university or work), and formal (made of heavy, black fabric, often embroidered, for weddings or for mourning).
As with all fashions, styles vary with age. Students, teachers, and working women wear manteaus with black trousers and a headcover in the shape of a wimple (maghna’eh) in black or a dark color, and if they are châdoris (i.e. they always wear a chador outdoors), with a chador on top. School uniforms for girls consist of loose overalls with pants made of the same fabric and a dark blue, gray, or black wimple.
Wearing a headcover has assumed an air of formality. In my daughter’s girls-only high school, where all staff are female and no males are allowed on the grounds during the school day, teachers wear black chadors, manteaus and wimples to school and then change to colorful scarves or shawls once inside, unlike the girls who remove their wimples upon entering the school and replace them before leaving the school. In this case, when no males are present, wearing a headscarf underscores the difference in status between teachers and students.
When out of uniform, many teenage girls sport tight, short overalls that look more like longish shirts, usually black, over tight denim jeans, although jeans and fashionable sneakers are common among all young women, whether they wear a chador or not. In fact, tourists can see young women dressing like this in the street, with the only difference that some will wear a chador over their top and jeans.