As public transit agencies across the United States raise fares, transit affordability has emerged a salient equity issue on the political agenda. With few exceptions, transit agencies do not provide means-tested discounts for low-income riders (federal policy only mandates senior and disability discounts). Our research investigates how the cost of public transit influences transit use and access to goods and services among low-income riders, and whether a low-income fare policy instrument could improve the quality of life of low income transit users. A two-month randomized controlled evaluation was conducted to study the effect of providing a 50% discounted MBTA fare to low-income individuals in the Boston region. Individuals receiving food stamps (SNAP) benefits were recruited and randomly assigned to either receive a 50% discount smartcard or a regular smartcard. All participants provided daily travel diary information on the purposes of their transit trips via a custom developed automated SMS/text-based mobile-phone ChatBot software tool. Compared to the control group receiving a standard smartcard, those in the treatment group with a 50% discounted smartcard took, on average, approximately 30% more transit trips, as well as more trips to health care and social services. The research also indicates that compared to the average MBTA rider, the low-income individuals participating in the study took more of their trips during off-peak times and were more likely to pay with their smartcard using stored value (“pay as you go”) rather than purchasing seven-day or monthly passes.