Photos and iMovie don't support direct drag and drop between the apps, but there are two ways to bring images from Photos into iMovie projects.
Use the Libraries browser in the iMovie sidebar
You can access your Photos library from within iMovie:
- In the left-hand sidebar of the iMovie window, select Photos Library.
- Click the pop-up menu at the top of the image browser to choose a content category—My Albums, Albums, Years, Collections, Moments, or Places.
- When you find the photo you’d like to use, drag it into the Timeline.
Drag and drop from the Desktop
You can drag photos from your Desktop and drop them into iMovie:
- Drag the photo you’d like to use from Photos to your Desktop.
- Drag the photo from the Desktop to the Timeline in your iMovie project.