The relationship between information and control interests social scientists; however, much prior work has focused on organizations rather than families. Work on interactive information behaviors has also focused on organizations and on collaboration rather than conflict. Therefore, in families managing chronic illness, we investigated information behaviors in the context of health‐related social control and the impact of control on patient health behavior. We conducted a qualitative analysis of interviews with 38 family groups and 97 individuals over 2 years. Findings revealed conflictual information behavior, which led to competitions for control and influence between family members and patients. In response to perceived patient health behavior‐related problems, family members sought, shared, and used information for social control of patients by enforcing norms, leveraging expertise, performing surveillance, and structuring the environment. These behaviors clashed with patients' interests and perspectives drawn from their own information acquisition. Patients responded by assessing family‐presented information and using information to resist or appease norm enforcement, refute or agree with expertise, and permit or block surveillance. Over time, some patient behaviors changed; alternatively, patients blocked family access to information about themselves, or family members retreated. The results challenge presumptions of benefit and harmony that have characterized much prior information behavior research.