Two studies investigated the process by which sensemaking occurs in naturalistic settings and used those findings to develop training interventions to improve sensemaking skills. The first study conducted simulation interviews with Army Information Operations (IO) officers to observe the way they made sense of message streams during unfolding scenarios. Cognitive Task Analysis techniques were used with six highly experienced and six novice IO personnel to tap their interpretation of unfolding events. Reasoning strategies were found to be similar, but the experts drew on more domain knowledge to generate more powerful inferences. In the second study, 10 USMC second lieutenants were charged with making sense of unfolding events in a set of four infantry ambush scenarios. These sessions tested the use of electronic Decision Games (eDGs) for enhancing sensemaking skills and subsequent situation awareness. Expert infantry tacticians mentored the students, and the research team collected data on the students' situation awareness throughout the scenarios. Performance data from control and test eDGs show significant improvement in sensemaking as a result of mentoring and practice on the training scenarios. This improvement is attributed to a richer fragmentary mental model of the ambush operation, which in turn provides a "better" frame from which to undertake the process of sensemaking. These findings, coupled with incident data from navigation, nursing, and AEGIS operation studies, have produced a Data/Frame model of sensemaking that describes how individuals use a frame (a story, script, or map) to select information from the environment and interpret it to generate an assessment of the situation. In addition, this research shows promise for utilizing expert/novice differences and scenario-based techniques to enhance sensemaking skills.