I thought that the cover of Daniel Gilbert's Stumbling on Happiness (Knopf, 2006) was quite striking when I came upon it in a bookstore. Then a few weeks later I picked up Sonja Lyubomirsky's The How of Happiness (Penguin, 2007) from a library shelf thinking it was the same book. Rather a misstep on Penguin's part, wouldn't you say, so closely echoing the cover design of another recent work of popular psychology on the same topic? Lyubomirsky's is a self-help book, so it will appeal to a somewhat different audience. But they're still likely to be shelved in the same section of the bookstore. And given that Gilbert provided a blurb for Lyubomirsky's book, surely someone on her team ought to have been aware of his book and noted the similarity? I bet he was a was a bit taken aback on first sight of his complimentary copy.