I'm not usually one to review books on here (I think plenty of others do, and do a great job!) but as I came to this page to purchase yet another copy of this book to gift a friend, I found myself browsing through some of the reviews and had to respond to some of the criticisms. In essence, I think some of the reviewers here have missed the point entirely.(One criticism that I do agree with is that the book is heavily focused on the American 20-something experience, yet I do not fault Jay for this--she is an American psychologist, has likely treated predominantly American clients, and is writing for a largely American audience. The "early life crisis" of the 20-something that can't decide on a career is a far cry from the issues faced by their peers in impoverished or warring nations, or even those that are similarly developed but culturally distinct. That said, just as I, a 20-something American woman, wouldn't pick up a self-help book written for senior men, I wouldn't pick one up, for example, for those coming of age in China. It's not that one's better or worse than the other, it's just that only one applies to me. I don't think you can get angry about a book addressing the 20-something experience in America when it's written by an American author who makes no assertion that she's writing for a universal audience).1) "This book didn't apply to me because I'm in my mid/late 20s and/or have my life together already and/or I already knew all the advice given."On one hand, I want to congratulate you, but on another, I think you might have fallen into the millenial trap of being narcissistic and blindly self-assured. Of course many people do graduate college, find a job in a related field, and transition into adulthood without issue. But I imagine that for every person following this path that winds up successful and content with their lives, there are a dozen that end up burnt out and disillusioned by 35, and are forced to reevaluate their decisions and start over. It's not just about choosing a career either--the book proposes mindful selection of friends, partners, and life experiences. With the top speed of modern life, it's easy to continue going through the motions without stopping to think about what you're doing. Even if you feel you're headed in the right direction, what is the value lost by taking the time to consider what you really want? (Also, if you really "have it all together" already, why did you read this book in the first place?!)2) "It places too much emphasis on finding a partner/having children/living the traditional "American dream."There seems to be a failure of taking the information presented and interpreting the message as it applies to your own life here. The "hook up" culture of 20-somethings and the prevalence of domestic abuse are real issues in the US right now. Fertility is also a hot topic, with popular media generating this idea that ANY woman can get pregnant with a little work and hormone injections well into their 40s. Once again, this is about mindfulness, not following a prescribed path. Not interested in settling down with one partner just yet? Fine! But does that mean you want to jump from meaningless hook up to meaningless hook up without learning about yourself and developing an idea of how you'd like your adult relationships to be? Sure you're not ready for kids now, but is it something you see for yourself eventually? How important is it to you? The answer may be not very, and that's okay! The point is to actually THINK about it and be intentional in the choices you make.3) "This is just one person's opinion, she does nothing to back it up."Honestly, this is just ludicrous. Jay integrates *peer reviewed literature* with her own clinical experiences and makes reasonable inferences about patterns in 20-something behavior based on them. You can disagree with the message, but saying that it's being pulled from thin air is just ignorant.4) "This book was depressing because it made me feel badly about where I am in my life by my mid/late 20s or 30s."I understand that some of the information presented can be anxiety-provoking and can make you question your life choices--that's the point! Read the case studies of 20-somethings who were depressed and anxious in their dead end jobs and relationships, they all found a pathway to a more fulfilling life. Even if past the "sweet spot" of the early/mid 20s, this book can help you to understand the reality of beginning a career or a family later in life. If you're unhappy with your life and expect a pat on the head and a participation trophy, ("it gets better!") this book is not going to help you. If you're lost, unhappy, unfulfilled, or depressed about the state of your life, this book can help you to see these problems as approachable, and models the shift in thinking that will help you to design the life you want for yourself. But 250ish pages written by a psychologist who you haven't met will NEVER be a catch-all solution.I think this is an important book that those in their late teens or twenties would do well to read, and that older demographics could use to better understand how to support the growth of the 20-somethings in their lives. As with ANY literature, it should be read with a critical eye and with careful consideration of your own experiences, goals, and personal beliefs. The Defining Decade is not written to be a panacea for every struggling 20-something. It does go against the rhetoric 20-somethings are hearing and provide honest, objective examples of how and why taking action in early adulthood is important.