This work presents the evaluation of a first-of-its-kind intervention to improve the management of allergies among workers in a largely blue-collar industrial setting. This intervention implemented eight educational strategies focusing on appropriate medication use in the context of a controlled, nonrandomized, pre-post quasi-experimental study design. Program implementation occurred during summer 2001, with change assessed by means of measures of health and productivity, developed from employee surveys timed to occur at the height of the spring and fall allergy seasons, and measures of contemporaneous adverse events developed from administrative databases. Evidence of improvement was found at one experimental site but not at the other experimental sites or the control site. Tests using exploratory and confirmatory analyses were conducted of two hypotheses linking the gains of this site's allergy group to 1) intervention process changes and 2) changes in allergy severity caused by seasonality. Neither hypothesis is found to fully account for the explained variation between sites. Similar pre-post productivity gains for other disease groups at this site relative to the other sites suggest that the inclusion of other unmeasured variables would improve explanation; e.g., the responses of employees with chronic disease to notably challenging labor negotiations at this site. The implications for promoting behavioral change in the management of the impact of disease on productivity are explored.