I think it depends on the romper! I have a bunch of them and some are more casual than others. I have a nautical cotton romper (blue and white striped) that I wear with red espadrille wedges, a pink floral silk romper that I wear out at night with a skinny black leather moto jacket and black studded ankle boots, a tweed gray romper that I wear when the seasons are turning with a long black cardigan and ballet flats...etc.