Lightroom 4.2

The only way to do batch editing in Lightroom is to edit one image, copy the settings from that image, then paste the settings to the batch of selected images. So:

1. Edit an image.

2. With that edited image still selected, either do Ctrl+C (CMD+C on a Mac) to copy all the edit settings, or do CTRL(CMD)+Shift+C to bring up the Copy Settings dialog where you can select which edit settings you wish to copy.

3. When the settings are copied, select all the images that you want to apply the copied settings to, then do CTRL(CMD)+Shift+V to paste those settings to all the selected images.