In 2008, there were more than 5,200 workplace fatalities in the United States (BLS, 2010b). During the same time period, U.S. employees missed almost 1.1 million days from work (BLS, 2010c). Accidents are unexpected outcomes that result not only from individuals' behaviors, but also from contextual factors (Krause, 1997;Reason, 1990). Therefore, unsafe behaviors have to be interpreted according to a combination of what is occurring in the environment and what the individual is doing in that environment. The present study sought to create a more comprehensive model of safety by means of macroergonomics. Macroergonomics utilizes sociotechnical systems theory to posit that a work system is composed of a personnel subsystem (i.e., ways individuals perform tasks), a technological subsystem (i.e., tasks to be performed), and external factors (Hendrick, 2002a).Perceived control over work hours, an aspect of the technological subsystem, was examined as an antecedent of work-family conflict. Supervisor instrumental support, an aspect of the personnel subsystem, was examined as a moderator of the relationships between perceived control over work hours and work-family conflict. Supervisors have an imperative role in employees' perception of control over their work hours (Kelly & Moen, 2007). Supervisor instrumental support was also hypothesized to moderate the relationships between work-family conflict and safety performance. Supervisors who support their employees in their work-family matters exceed mandatory requirements set forth to protect workers' safety and health (Mearns, Hope, Ford, & Tetrick, 2010).A majority of the 360 participants in the present study were grocery store employees who worked in the front end of the store as cashiers. Job tenure in this particular grocery store chain was an average of 7 years (SD = 5.96) and the average number of hours worked per week was 31 (SD = 8.55). The employees were an average age of 38 years old (SD = 15.25). Two hundred and sixty-two (73%) of the participants were female, 330 (92%) were White, 196 (55%) employees were married or living as married, 146 (41%) employees identified themselves as parents with children living at home, and 58 (16%) employees provided elder care.The data were analyzed using a moderated mediation model. An employee's perceived control over his/her work hours was negatively associated with work-to-family and family-to-work conflict. Work-to-family conflict was not significantly associated with either safety compliance or participation. In contrast, family-to-work conflict was significantly associated with both safety compliance and participation. These findings replicate Cullen and Hammer's (2007) findings that family-to-work conflict, but not work-to-family conflict, is negatively associated with safety compliance and participation. The replication of these significant findings gives support to macroergonomics' assertion that external forces (i.e., family) can affect the safety of employees.All of the meditating and moderating relationship...