Context: Federal law requires property owners to disclose the presence of known lead-based paint and/or lead hazards to potential home buyers and renters in homes built before 1978. Objective: Using 2015-2016 randomized survey data, we measured lead and radon knowledge, awareness, and exposure avoidance practices. Setting: Home buyers from 4 US states (Illinois, Minnesota, North Carolina, and Ohio). Participants: 477 recent, single-family pre-1978 dwelling home buyers. Main Outcome Measure(s): Predictors of the home buyer decision to purchase the home during the entire home buying experience based on their understanding of health issues related to lead-based paint and radon exposure. Results: Personal networks (22%) and real estate agents (21%) were the most common sources of health-related lead information. Many home buyers (77%) reported that their awareness of lead did not affect their purchasing decision, and 78% could not confirm that their homes were tested for lead. Respondents who understood lead-related health effects were 5.4 times more likely (95% CI, 1.7–17.5) to have their decision to buy a home affected when their real estate agent discussed lead-based paint issues. Many home buyers reported either they did not remember (37%) or did not sign (20%) the federal law requirement that property owners reveal known lead paint hazards to prospective buyers before a property is sold. Home buyers with awareness of health issues caused by radon were 1.7 times (95% CI, 1.4–2.1) more likely than those who understood lead-related health issues to have their decision to buy the home affected. Conclusion: Real estate agents play an important role to increase awareness of potential lead-based paint health issues when people buy older homes. Home buyer knowledge, awareness, and practice of radon exposure prevention was greater compared to lead exposure prevention. More than half of home buyers did not sign or remember signing lead disclosure paperwork.