Global climate change has great potential for escalating the number and duration of extreme heat events in California. California accounts for 16% of U.S. crop production, and over 450,000 people are employed in agriculture, with more than two-thirds being of Latino ethnicity. Despite Cal/OSHA regulations which specify that potable water, toilets, shade and rest be provided to agricultural workers, heat related illnesses and deaths still occur. The MICASA Study is a population-based sample of 467 hired farm worker households from Mendota, in California's Central Valley. 474 study participants completing follow-up interview and working in agriculture in the year prior are included in this analysis. Men reported an average of 222 d (SD=69.7) of work compared to 148 d (SD=67.3) for women (p<0.0001). Over 91% of participants reported receiving training on heat-related illness, but level of heat illness knowledge was moderate with 70% responding correctly to 4-5 questions. Knowledge about acclimatization was low, with 44% severely underestimating the time required, and water consumption was low at an average of 10.7 drinks per day. Results suggest important areas to target for heat illness prevention in farm worker populations and that gender specific approaches may be needed for effective heat illness prevention.