Taking advantage of a recent relaxation of Japanese government's data release policy, we conduct the first cross-national analysis of micro data from Japan's Employment Status Survey and its U.S. counterpart, Current Population Survey. Our focus is to document and contrast changes (or lack thereof) in long-term employment and job security over the last twenty five years between the two largest advanced market economies. On the one hand, we find that in spite of the prolonged economic stagnation, prime-age male workers with at least 5 years of tenure in Japan continued to enjoy much higher job stability than their U.S. counterparts consistently over the last twenty-five years. Most remarkably Japan's "Lost Decade" is found to have little discernible adverse effect on job stability of this group of Japanese employees. On the other hand, we find that job stability for mid-career hires and youth workers did deteriorate in Japan over the last twenty-five years. Our cross-national regression analysis of the odds of job loss confirms the consistently more important role that seniority plays in protecting workers from job loss in Japan than in the U.S., and uncovers that such Japan-U.S. gap in seniority's influence in job stability widened over the last twenty five years. It is the U.S. economy with the longest economic expansion not the Japanese economy with the longest economic stagnation in which employment stability and job security deteriorated. As such, contrary to the conventional wisdom, our findings point to the absence of convergence of the Japanese and U.S. systems. However, our job retention analysis, combined with our regression analysis of the odds of job separation in Japan over 1982-2007, shows that mid-career hires, young new job market entrants, and college-educated women in Japan were less fortunate, with their job stability deteriorating significantly. (JEL: J63, J64, J41, P52)