As I was browsing recent literary works at the YU Seforim sale and realizing that at 30 I am old compared to these young college students, I stumbled across a book that caught my fancy.  Essentially, Ms. Margolese, provides insight as to why orthodox jews (defined as keeping shabbas and kosher) become less observant and in many instances not observant at all.  Of course, I was intrigued for several reasons, first I, like many Frum From Birth ("FFB") people have friends and/or family that have gone off the derech and as a father of two little girls wanted insight why people go off the derech.
 
The first 100+ pages are quite interesting, most dealing with people, including Ms. Margolese's, who writes of her own experiences, who are off the derech because of a negative experience in a religious setting.  This could be a teacher and/or parent using the medium of religion to put excessive pressure on someone and when that person gets older the negative feelings lead them astray.  There are even some instances, one sticks out where a guy lived on the Westside and just did not feel any religion on shabbat and the like, deeming the Westside to simply be a scene.  He did admit that he went off the derech and came back but looked at the Westside as the reason.  While this is true, Ms. Margolese, makes these people have minds of simpleton.  What I mean is, I would hope someone who had a negative experience would at least think more than just go off the derech.  It should also be noted that Ms. Margolese's study is not scientific (i.e. she did not meet a sample of 500 people who are off the derech), rather she used internet questionaire for alot of her infornation.
 
Next Ms. Margolese gets into the philosophical reason of "overthinking" religion.  Ms. Margolese admitted that this is a smaller segment, but I have always felt those who "overanalyze" religion are really just looking for an excuse to not practice.  Ms. Margolese spent a large section on the philosophical and psychological, seemingly repeating her analysis in every which way.  This is where the book became a struggle to completely read and could have been written in 25 pages rather than 125 pages.
 
A few items which I think Ms. Margolese should have stressed in greater detail was the affect of the college experience on leading people off the derech and the unequivocal freedom people have in today's society.  Experience in college can make or break someone and it really does not matter if you attend a highly Jewish college (YU, Columbia, Penn, etc.), there are so many outside influences that can change what one prioritizes and how one conducts his/her life.  Ms. Margolese did mention people who never had a negative experience but rather just have made a "life decision" to not observe.  This, I think from a parents perspective can be most scary because you may try to have provide a positive experience for your kids about Judaism, observance, holidays, etc., but in the end a kid may just decide it is easier to not keep kosher, not keep shabbas but at the same time be a good person.
 
In the end, Ms. Margolese concludes as I predicted she would at about page 175 that there is not defintive answer as to why people go off the derech.  Every person has his/her own reasons.  Because we live in such an assimilated and free society, it is easier than ever to wake up one morning and decide religion just is not for you.  This is what should scare clergyman and outreach organizations, is that while the baal teshuvah movement may be growing when someone goes off the derech (obviously there are varying degrees), it could lead to intermarriage which in turn can lead to children being unaffiliated and not even having one parent, let alone two parents who are Jewish.