How can I align the contents of a layer to the center of the image?

cut and paste. You need to see the whole image.

Is that the only way? What if I want to have the contents centered horizontally but not vertically?

do what buglover said, and just move it holding the ctrl+shift key
it will still move but it will be more direct.
I hope that helps, it prob would help us to know what it is you're trying to accomplish before we answer though.

Thanks, I didn't know about the ctrl + shift trick. That'll come in handy in the future. I was just wondering if I could center the contents without having to copy and paste because I'm working with text. Or is there a way to copy and paste text without the copy being rasterized?

When I use text in photoshop, I AWAYS make it first in a program like Illustrator, then import the .eps file into Photoshop, it comes out cleaner for some reason. but I really hate putting text on pictures, even for comic effect. unless its needed, like signs or the like.... but for design, I always leave the text in Illustrator, and import the photoshopped picture there. You can however go Layer>Rasterize>Layer, and that will turn the text into a layer and be part of the picture, but you cant edit it then..

I think I may have screwd up the shift thing.. I think its really optn + shift.. thats also on a MAC
but if youre just trying to get text right in the middle of the image, do the text then copy it put your doc to 100% and paste, it should put it right in the center of the page, then do the optn +shift and move it where you want.
I hope that helps ya out, now you have to chop something for a contest, its the rules man

1. Click on the background layer in the layers palette.
2. Click the link layer box (the one next to the eye on the layers palette) on the layer you wish to position.
3. The option bar (at the top, under the menu items) will display the alignment options there you can choose to align either vertically, horizontally or vertically and horizontally.

thank you. at least one person knows that photoshop will do this for you automatically. +1 point for you spirtle.

pete, thats the easy way... pfft who wants easy?

If this is that hard--In "View" choose rulers.Line it up w/ the crosshaires.

1. Select layer you want to center.
2. Hit ctrl-A (selects entire canvas).
3. Select the mover tool (arrow)
4. Look on the top bar below the menu bar and hit both the horizontal and vertical centers.