Silk and satin are where a dress starts to move, and movement is most of what people mean when they say a dress looks elegant. The names here tell you the fabric, so I will keep to what they say: silk, silk blend and satin, in slips, shirtdresses and belted midis.

The Reformation Jeany Silk Dress, Lilibeth Silk Dress and Daniela Silk Dress are the simplest way into the group, plain silk shapes that look better the less you add to them. The Saloni Lea Silk Dress and the STAUD Portia Silk Blend Dress are in the same family. I would wear any of them with a leather jacket in the afternoon and bare shoulders at night, because that range is the point of silk.

If you want a pattern, the Johnny Was Yammilet Silk Embroidered Midi Dress is the one to look at, since the embroidery already does the work and you need almost nothing else. The Marella printed silk shirtdress is the daytime version of the same idea, and the Elie Tahari The Kataleya Silk Blend Belted Shirt Dress gives you a defined waist with a collar, which suits a work lunch or an office event better than a slip would.

Then the satin group. The Donna Karan New York Satin Belted Midi Dress is the sleek one. The Mint Velvet Layered Satin Knit Midi Dress adds a knit layer, which makes it softer and easier to wear in cooler months. The AQUA Oversized Floral Stretch Satin Midi Dress and the AQUA Lace Trim Satin Midi Dress show you the stretch and the lace side of satin.

A practical note: hold satin up to a window light before you buy it in a store, or look at it on a moving model online. You want to see how it falls, not just how it shines.

The Emily Post Institute lists a dressy cocktail dress and your dressiest little black dress alongside a floor-length gown for black tie. So a gown is the classic answer, but not the only one. If an invitation says black tie and you want the real thing, this grid is for you.

Begin with the drama. The Cinq à Sept Antonella Hand Sketched Floral Gown is the one floral here and it makes a wedding guest look confident without a single accessory. The Amur Reese Silk Cascade Gown is for the person who wants movement as she walks in. The Miss Circle Fabienne Mesh Cap Sleeve Mermaid Gown is the most fitted of the lot, with mesh at the shoulder, so try it with a good pair of heels in the room to check the hem.

The satin gowns are the largest group, and AQUA does most of them: the Mikado Strapless Midi Gown, the One Shoulder Satin Column Gown, the Stretch Satin Ruched Gown, the Long Double Face Satin Halter Gown and the Long Satin Lace Trim Bias Gown. The Met says Madeleine Vionnet pioneered many innovations the bias cut permitted, and it is worth knowing the cut when you see it: a bias gown skims instead of clinging.

The JLUXLABEL Down The Aisle Satin Gown, the Donna Karan New York V Neck Satin Gown and the Eliza J One Shoulder Satin Gown are the classic shapes, and I would call them the safest places to begin.

What I would skip: a gown you cannot walk up stairs in. Lift the hem, take a few steps, sit down and lean forward in the fitting room, and skip any gown where you are managing the fabric instead of enjoying the party. The same goes for any strapless cut if you know you will tug at the neckline all night.

Here is how I would choose. Read the invitation first. Semi-formal or cocktail points to a midi, black tie points to a gown, and anything with the word garden or lunch points to something lighter, so start in the first grid.

Then check the length against your shoes. Stand in the flat shoes you might actually wear and see where the hem lands, then do it again in heels. A midi that works with both is a smart find, and a gown that only works with one heel height needs a tailor.

Last, try the move test. Reach, sit, walk, hug someone. The dress that lets you forget about it is the elegant one, whatever the label says. If you want to keep browsing, I also put together Dresses and Occasion Pieces, Ranked and Burgundy Dress.