Our theoretically driven cluster-randomized cohort control study sought to understand how psychosocial safety climate (PSC)-a climate to protect worker psychological health-could be built in different organizational change scenarios. We drew on event system theory to characterize change (planned vs. shock) as an event (observable, bounded in time and space, nonroutine) to understand how events connect and impact organizational behavior and features (e.g., job design, PSC). Event 1 was an 8-month planned intervention involving training middle managers to enact PSC in work units and reduce job stressors. Event 2 was the shock COVID-19 pandemic which occurred midintervention (at 4 months). Three waves (T1, 0 months; T2, 4 months; T3, 8 months) of data were collected from experimental (295T1, 224T2, 119T3) and control (236T1, 138T2, 83T3) employees across 22 work groups. Multilevel analysis showed in Event 1 (T1T2) a significant Group × Time effect where PSC (particularly management priority) significantly increased in the experimental versus control group. Under Event 2 (T2T3), PSC was maintained at higher levels in the experimental versus control group but both groups reported significantly increased PSC communication and commitment. Results suggest that middle management training increases PSC within 4 months. Event 2, COVID-19 was shocking and its novelty, disruption, criticality, and timing in Australian industrial history enabled a strong top management response, positively affecting the control group. PSC may be sustained and built in times of shock with top management will, the application of PSC principles, and a top-level pro-psychological health agenda. (PsycInfo Database Record (c) 2021 APA, all rights reserved).