Background: Women in India continue to have high rates of anemia, especially in critical periods of adolescence and pregnancy. Anemia persists despite decades of government programs aimed at combatting anemia, including through the provision of iron folic acid tablets (IFA). With growing access to mobile phones and social media, even among women, mobile interventions hold potential for influencing knowledge and behaviors. Social media consumption, including on Facebook, is high in India. However, little research has explored if women can be reached with health messages using social media, if data can be collected through this mechanism, and if interventions using social media impact knowledge and behaviors surrounding important health issues such as anemia. The aims of this study were to test an advertising campaign on Facebook about anemia and IFA to women, collect data through social media, and measure its impact.Methods: A baseline survey and two follow-up surveys were sent to women via Facebook in 2019 in two states of India: Madhya Pradesh and Uttar Pradesh. Between each round of data collection, a set of advertisements based on gaps in knowledge and practices identified in the baseline on anemia and IFA were delivered to more than 3 million women on Facebook. Using this data, we analyze current knowledge and behaviors around anemia and IFA and look at differences by socio-demographics including age, Marital status, and pregnancy. Using logistic regression models, we then look for evidence of a significant change in knowledge and behaviors between rounds of data collection.Results: We find that while general knowledge about anemia was high, especially related to its importance in pregnancy, misperceptions persist, such as that it makes babies large and delivery difficult. Only about 15% of the population was currently taking IFA, although nearly 50% noted that they had at some point. Younger women had lower levels of knowledge and practices. Findings about the impact of the Ad campaigns were mixed, with some indicators changing in positive and some in negative directions and no clear trend between surveys. Two indicators that were of high focus in the Ad campaigns changed in the desired direction after both ad campaigns (iron can make labor/delivery difficult and iron supplements are only for women who have anemia).Conclusions: Overall, this study shows that a social media campaign about anemia has the potential to reach a large number of women in India, including young women, who are hard to reach if they are not in school or currently pregnant and seeing a physician. This study shows that it is possible to collect data from women through social media and measure the impact of an intervention. More research is needed to know if social media is an effective approach to actually change attitudes and behaviors related to anemia, or other important health concerns.