This article provides an example of how Perinatal Periods of Risk (PPOR) can provide a framework and offer analytic methods that move communities to productive action to address infant mortality. Between 1999 and 2002, the infant mortality rate in the Antelope Valley region of Los Angeles County increased from 5.0 to 10.6 per 1,000 live births. Of particular concern, infant mortality among African Americans in the Antelope Valley rose from 11.0 per 1,000 live births (7 cases) in 1999 to 32.7 per 1,000 live births (27 cases) in 2002. In response, the Los Angeles County Department of Public Health, Maternal, Child, and Adolescent Health Programs partnered with a community task force to develop an action plan to address the issue. Three stages of the PPOR approach were used: (1) Assuring Readiness; (2) Data and Assessment, which included: (a) Using 2002 vital records to identify areas with the highest excess rates of feto-infant mortality (Phase 1 PPOR), and (b) Implementing Infant Mortality Review (IMR) and the Los Angeles Mommy and Baby (LAMB) Project, a population-based study to identify potential factors associated with adverse birth outcomes. (Phase 2 PPOR); and (3) Strategy and Planning, to develop strategic actions for targeted prevention. A description of stakeholders’ commitments to improve birth outcomes and monitor infant mortality is also given. The Antelope Valley community was engaged and ready to investigate the local rise in infant mortality. Phase 1 PPOR analysis identified Maternal Health/Prematurity and Infant Health as the most important periods of risk for further investigation and potential intervention. During the Phase 2 PPOR analyses, IMR found a significant proportion of mothers with previous fetal loss (45%) or low birth weight/preterm (LBW/PT) birth, late prenatal care (39%), maternal infections (47%), and infant safety issues (21%). After adjusting for potential confounders (maternal age, race, education level, and marital status), the LAMB case–control study (279 controls, 87 cases) identified additional factors associated with LBW births: high blood pressure before and during pregnancy, pregnancy weight gain falling outside of the recommended range, smoking during pregnancy, and feeling unhappy during pregnancy. PT birth was significantly associated with having a previous LBW/PT birth, not taking multivitamins before pregnancy, and feeling unhappy during pregnancy. In response to these findings, community stakeholders gathered to develop strategic actions for targeted prevention to address infant mortality. Subsequently, key funders infused resources into the community, resulting in expanded case management of high-risk women, increased family planning services and local resources, better training for nurses, and public health initiatives to increase awareness of infant safety. Community readiness, mobilization, and alignment in addressing a public health concern in Los Angeles County enabled the integration of PPOR analytic methods into the established IMR structure and [the design and implementation of a population-based l study (LAMB)] to monitor the factors associated with adverse birth outcomes. PPOR proved an effective approach for identifying risk and social factors of greatest concern, the magnitude of the problem, and mobilizing community action to improve infant mortality in the Antelope Valley.