The first chapter of this dissertation examines the effect of insurance mandates on infant immunization rates. Immunizations are one of the greatest public health achievements of the 20th century. While US infant immunization rates have been increasing in the last 20 years, the cost of fully immunizing a child with all recommended vaccines has almost tripled. This is partly due to new additions in the list of recommended vaccines, but also due to the use of new, safer, but more expensive technologies in vaccine production and distribution. In recent years, many states have mandated that recommended childhood vaccines be covered by private health insurance companies. Currently, there are 33 states with such a mandate. In this paper, I examine whether the introduction of mandates on private insurers affected immunization rates. Using state and time variation, I find that mandates increased the immunization rate for three vaccines — the diphtheria-tetanus-pertussis, polio and measles vaccines — by about 1.8 percentage points. I also find evidence that the mandates shifted some vaccinations from public to private sources. The second chapter of this dissertation studies the issue of whether concerns about autism affected vaccine takeup. In the wake of strong claims that there existed a link between autism and the measles-mumps-rubella MMR) vaccine, which was refuted by later research, I examine whether fewer parents immunized their children. This task becomes difficult as the timing of the controversy in the US coincided with expansions in medical access for children and other programs that affect childhood immunizations, as well as another controversy regarding mercury containing preservatives in childhood vaccines. Using a time trends analysis and a few differencing strategies that compare the take up of MMR to other vaccines, I find that the MMR-autism controversy led to a decline of about 2 percentage points in the take up of MMR and a negative spillover on other vaccines. I find some evidence that more educated mothers responded more to the controversy, which is consistent with more educated individuals absorbing health information more quickly. However, this disparity persisted even after new research and information about the lack of such link became widespread in the media. The third chapter of this dissertation analyzes the effectiveness of a peer counseling breastfeeding support program for low income women in Michigan who participate in the Women, Infants and Children WIC) program. Because there was excess demand for services provided by the program, many women who requested to participate were not subsequently contacted by the peer counselors. We compare the breastfeeding outcomes between the two groups and identify the effectiveness of the program based on the differences between the women who requested to participate and were enrolled relative to those who requested participation, but were not contacted due to lack of capacity. Our analysis uses survey data from the program as well as administrative data from Vital Records, Medicaid, and WIC from the state of Michigan. After providing evidence that our key assumption in identifying the effect if program is consistent with the data, we estimate that the program caused the breastfeeding initiation to increase by about 27 percentage points and the mean duration of breastfeeding to increase by more than 3 weeks. The support program we evaluated was very effective at increasing breastfeeding among low income women who participate in WIC, a population that nationally breastfeeds at rates well below the national average and below what is recommended by public health professionals.