You can wear toe socks in Fivefingers but it's a question of preference. Wearing socks with Five Fingers Shoes can reduce transition time for sensitive feet, friction/hot spots, and odor from sweat, and increase thermal regulation.

When it’s cold, the more the layers the better. In winter, as much as 90% of users wear socks. There are many benefits of toe socks that most of us really don’t know much about. Like why wear toe socks plus toe socks vs normal/regular socks. There are many benefits of toe socks for running and benefits of wearing toe socks.

The things to remember before buying toe socks:

• Wearing cheaper knock-off socks is always more likely to lead to discomfort.
• High-quality toe-socks might seem expensive, but you really do get what you pay for. The better the quality of the socks, the better they will combine with footwear.
• Good socks will offer a fit that’ll create less friction and offer more compression, which means less sizing issues.
• You don't need a larger size in Five Fingers to allow for toe-socks.

There’s no rule to say you can’t, so it comes down to what you think feels best. But not a must have.