The primary objective of this study is to describe human milk sharing practices in the U.S. Specifically, we examine milk sharing social networks, donor compensation, the prevalence of anonymous milk sharing interactions, recipients' concerns about specific milk sharing risks, and lay screening behaviors. Data on human milk sharing practices were collected via an online survey September 2013–March 2014. Chi‐square analyses were used to test the association between risk perception and screening practices. A total of 867 (661 donors, 206 recipients) respondents were included in the analyses. Most (96.1%) reported sharing milk face‐to‐face. Only 10% of respondents reported giving or receiving milk through a non‐profit human milk bank, respectively. There were no reports of anonymous purchases of human milk. A small proportion of recipients (4.0%) reported that their infant had a serious medical condition. Screening of prospective donors was common (90.7%) but varied with social relationship and familiarity. Likewise, concern about specific milk sharing risks was varied, and risk perception was significantly associated (P‐values = 0.01 or less) with donor screening for all risk variables except diet. Understanding lay perceptions of milk sharing risk and risk reduction strategies that parents are using is an essential first step in developing public health interventions and clinical practices that promote infant safety.