There are numerous ways to convert an image to black and white, each bringing with it its own balance of efficiency and artistic control. This method shows you how to really take the reins using just Lightroom.
Coming to you from Unmesh Dinda of PiXimperfect, this helpful video will show you how to use a combination of tools to create a dramatic black and white conversion in Lightroom. I generally prefer to stay in Lightroom whenever I can, only switching to Photoshop when I absolutely need to, as I just find it keeps me more efficient. The nice thing is that Lightroom has a lot more capabilities than might seem apparent at first glance, and with a little practice, you can get quite a bit of control over even local editing. When you're working with black and white, remember that painting with the light becomes even more important: use the interplay of highlights and shadows to shape the image and draw the viewer's attention where you want it to go. And of course, be sure you're shooting in raw to maximize your ability to push the file in the direction you want while still maintaining quality.