The Population Center Working Papers (PSC/PARC) Working Paper Series contains papers by researchers at the PSC/PARC. It serves as an outlet for pre-prints, for papers under journal review, and for background papers (e.g., for technical materials for which journals lack space) written by PSC/PARC Research Associates. The series also publishes submissions from students affiliated with Research Associates at the PSC/PARC with Research Associate sponsorship. The PSC/PARC series combines works previously published in the Population Studies Center Working Paper Series and the Population Aging Research Center Working Paper Series. Papers can be submitted by emailing: psc-library@pop.upenn.edu. Other archival series listed below include: Grand Challenges Canada Economic Returns to Mitigating Early Life Risks Project Working Paper Series and the Social Networks Project Working Papers and others.