“Since the junior groomsman is standing up with everybody, I would want there to be some uniformity—if there is uniformity at all,” Lee says. “A lot of grooms these days just say, ‘black suit, white shirt, black tie,' but let each groomsman pick the lapel they want. The junior groomsman should follow the same schematic as everyone else.” If groomsmen aren’t matching, likewise it’s fine for a junior groomsman to vary his look slightly, based on age and available sizing. As for personal flowers such as boutonnieres, “treat him with the same rules you would the groomsmen,” Lee says.
If you do want the junior to look the same as the others but his size isn’t available, you can always go the custom route. This would be a nice gesture for mature older teens, who may be able to get a lot of use out of the tux for a long time, whereas someone young will grow out of it quickly. Again, be aware of the financial constraint if you’re expecting mom and dad to pick up the tab. For younger junior groomsmen, plenty of tux and suit labels and rental companies offer kid’s sizing. Check out Appaman.