These are tough times for classic names. Even names that have stood as gold standards for timelessness are falling out of fashion: William, Katherine and Elizabeth have hit all-time popularity lows. Yet even in this naming climate, some traditional choices are thriving. Names like Amelia, Sebastian and Naomi have reached new popularity heights. What’s their secret?

To find out, I reviewed a set of old and familiar names that are currently at historic usage peaks. While the names run the style gamut, some common threads emerge as fashion drivers.

First, and most basically, all of the hot traditional names had been unpopular in recent generations. A top-100 popularity ranking during the years 1960-1990 is the kiss of death for trendiness. But countless names that were uncommon in the past remain uncommon in the present. For a traditional name to come on strong today, it needs something extra: a hook to draw in style-conscious parents. Here are seven of today’s most effective fashion hooks.

ORIGINS/USAGE

Old Testament. Names from the Old Testament/Hebrew Bible have a fashion edge, while most New Testament names are falling fast. In part this is a reaction to the past popularity of New Testament names, and in part it’s a matter of style. Ezra and Ari have more contemporary sounds than Eunice and Drusilla.

Mythological. Familiar mythological names are thriving, as long as they’re not too familiar. (Sorry, Jason and Diana.) This includes names I considered not quite traditional enough for my list, like Atlas.

British Isles. American parents are eagerly adopting names that in the past have only been popular in England, Scotland, Ireland or Wales. Names like Callum and Ronan sound established, but fresh.

SOUND

Multisyllabic. An unusually long rhythm can distinguish a name and set it apart. For male names “unusually long” means a minimum of three syllables; for female names, four syllables.

Liquid. The single hottest sound in names today is a liquid flow with no hard edges, and no consonant sounds other than L, M, N, R and W.

X’s and O’s. A final -o sound, or an X anywhere in the name, is a powerful attraction—enough to bring new popularity to long-neglected names like Arlo and Felix.

S Endings. A final S is considered distinctive and elegant, especially in classical-styled names like Silas and Cassius. Surnames ending in S are also coming on strong, led by the rising hit Brooks.

T Endings…Usually. A final T sound is a powerful attractor in a name, with two caveats. The T sound can’t be preceded by an R, as in Albert or Stewart, and the final syllable can’t be stressed. The French stressed -ette ending is still out of favor.

-ER Action Sounds. The -er ending is prized for its vigor, the sound of a “doer” as in occupational surnames like Hunter. The effect carries through to non-occupational names like Asher and Jasper.

You can see the power of these trends in this chart of 66 peaking traditional names. And if you find another, off-the-radar traditional name that fits more than one of the categories, it’s a good bet for fashion success.

In descending order of popularity: