In the wake of medical home certification, meaningful use, the Cures Act and the pandemic, it’s clear that virtually all of healthcare is now built on a digital foundation. EHRs are pervasive in the delivery system, and they are increasingly connected to practice management software, virtual visit and mobile capabilities, health information exchanges and population health platforms. As we consider the criticality of interoperability throughout this evolving digital ecosystem, I’m moved to reflect on the issue of interoperability in another time, the 1960s. As a child I had the opportunity to observe my father in solo pediatric practice. Sub-specialization was relatively new. General practitioners would come to him as a pediatric “specialist” to consult on their complex patients. There were no neonatologists, intensivists, hospitalists, or emergency physicians. He took care of his patients throughout their healthcare journey. If they needed surgery, he would follow them pre- and post-operatively along with the surgeon. In the office he and his nurse developed seamless workflows to manage patient care throughout the day. With house calls a routine component of the care model, he easily identified and assessed financial, social, and cultural issues that might impact his patients and integrated those assessments into his care plan. Even as this clinical picture harkens back to simpler times so too were the business models and regulatory requirements. Ambulatory care was largely a cash business. Many still had insurance that only covered hospitalizations. Even for those with coverage of ambulatory care, the patient typically paid the doctor and filed a claim to get reimbursed by the insurance company. Medicare and Medicaid weren’t even signed into law until 1965, and then took most of the rest of the decade to get implemented. HMOs were rare and geographically isolated, there was no such thing as prior authorization, and HIPPA was three decades away. In these simpler times, simpler technologies were sufficient to support interoperability needs. With so few hand-offs, face-to-face discussions and telephone calls for “sign-outs” worked just fine. Typewriters, carbon copies, and snail mail sufficed for formal sharing of assessment and plan in the referral process. Urgent or abnormal test results were delivered via a phone call to the ordering physician. In the absence of pagers and cell phones every doctor had an answering service that was kept informed of who was on call and how they could be reached, e.g., at home, in church, or at a restaurant. There was continuity of care stemming from less specialization, fewer sources of information, fewer providers in need of information, and a much simpler business model. Getting the right information to the right people at the right time was a fairly straightforward issue.