The purpose of this cross-national study was to gain a more comprehensive understanding about doctoral students in the United States and Chile and how their decisions to pursue a career in the life sciences field occurred throughout their lives. I interviewed 15 doctoral students from the Seven Lakes University (Chile) and 15 students from the West Coast University (US), using a life history approach. Analyses revealed that the degree of flexibility in the schooling system and the degree of individualism and collectivism of the social groups in which the students were learning science seemed to influence the informants' vocational decisions in three interrelated processes: (1) Deciding the informants' degree of interest and ability in science by the opportunity of choosing science classes and activities. The highly tracked Chilean system socializes students to science at an early age. The more flexible school system in the US enabled the interviewees to gradually decide about pursuing their interest in science; (2) Experiencing science as a collective learning process for the Chilean informants and an individualistic learning process for the US students; (3) Perceiving science differently at each life stage for both groups of interviewees including: Playing science, Studying science, Doing science, Working in science, Practicing Science in their doctoral programs. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]