"Stress factor" is defined as any internal or external influence that makes it more difficult for a school or district to carry out its basic mission of providing a high quality education to all its students, as well as to ensure that its students succeed on state and federal accountability measures. This report identifies 11 such stress factors. "Internal" stress factors include teacher layoffs, larger class sizes, fewer instructional days, fewer counselors, cutbacks in summer school, and security threats. "External" stress factors are declining enrollments, increasing childhood poverty, high unemployment, foreclosures, and health insurance coverage. In February 2013, EdSource sent e-mail surveys on these stress factors to California's 30 school districts with the largest enrollments. This report describes the multiple challenges faced by the school districts as "stress factors," and shows whether these stresses have increased, diminished, or stayed the same since 2011-12 and, in some areas, since 2007-08 before the recession began. [For a related report, see "Schools under Stress: Pressures Mount on California's Largest School Districts" (ED606405).]