Background: The recovery process of a psychiatric patient is related to his primary informal caregiver's style of coping with stress. There is insufficient literature on validations of instruments that measure coping styles in this population. Objective: To adapt and validate a scale to measure coping strategies in primary informal caregivers. Method: The adapted scale was based on the Extreme Coping Scale of López‐Vázquez and Marván. Items from that scale were adapted for application to informal caregivers. The scale was administered to 122 primary informal caregivers of patients from two psychiatric institutions in Mexico. Psychometric analyses were performed to determine the scale's properties. Results: The scale was composed of 20 items (six less than in the original scale) and two factors: (i) active coping (Cronbach's alpha = .837) and (ii) passive coping (Cronbach's alpha = .718). Discussion: The findings are discussed in the light of the importance of studying the relationship between coping styles and the well‐being of both informal caregivers and psychiatric patients. Implications for practice: The scale could be used by health practitioners and researchers to generate strategies to support the family caregiver, as well as to measure the results of interventions.