WordPress.com

You can control comment threading, paging, and comment order settings from the Settings > Discussion page in your WordPress.com blog dashboard.

With the threaded comments option, comment replies will appear directly below the relevant comment instead of in strict chronological order. That means you can reply to a comment that was left a month or even a year ago, and your comment will appear in just the right spot. You control the conversation by setting the number of levels allowed in your comment threads, from 1 to 10. We suggest setting threaded comments to about three levels deep, to keep the conversation focused. Here’s how that looks with the Contempt theme:

To save you and your readers from scroll-finger strain, you can break up comments into pages. You decide where to cut the thread, and whether to display the first or last page of comments as the starting point.

Comment ordering is up to you. If you want your readers to know what’s latest first, display the newest comment at the top. If you think it’s important to know the history of a conversation, display the oldest comment at the top.