Longitudinal data sets offer a wealth of information and allow researchers to seek answers to complex research questions. Two such data sets currently exist which permit detailed comparative analyses of the lives of today's young adults. Both studies have survey and interview components, contain representative state and province wide samples, and span 10 years. In the Life Patterns Project (1991-2001) a "pathways" metaphor has guided the collection of survey and interview data with high school leavers from Victoria, Australia to determine educational, occupational and other life outcomes. The Paths on Life's Way Project (1988-1998) has examined the lives, choices, and postsecondary education and work experiences of high school graduates from British Columbia, Canada. Both studies focus on respondents' lives in relation to changing social and cultural conditions. The purpose of our presentation will be to focus on the opportunities and challenges of collecting longitudinal data and conducting analyses both within each study and through cross-country comparisons. In doing so, we will address the following themes: staying abreast of current theories and analytical methods; training and maintaining student research assistants and other research staff; challenging our assumptions in order to provide accurate portrayals of the lives under investigation; and examining how funding shapes research.