Introduction : why does primary health care matter in the twenty-first century? / David Bishai -- I. Primary health care foundations -- Primary health care : history, trends, controversies, and challenges / Henry B. Perry -- Identifying countries with exceptionally rapid gains in life expectancy : a quantitative approach / Carolina Cardona and David Bishai -- Strategies to improve comprehensive primary health care performance in a district / Claudia Pereira, David Bishai, and Melissa Sherry -- Why well-supported health systems are necessary for vertical programs to succeed : lessons from polio eradication / Svea Closser -- Continuity between comprehensive primary health care and sustainable development goals / Melissa Sherry and David Bishai -- Four principles of community-based primary health care : support, appreciate, learn/listen, transfer (SALT) / Marlou de Rouw, Alice Kuan, Philip Forth, Rituu B. Nanda, and Luc Barrière Constantin -- II. Country case studies of primary health care at scale and the way forward -- Bangladesh's health improvement strategy as an example of the Alma-Ata declaration in action / Taufique Joarder and Ferdous Arfina Osman -- Ethiopia : expansion of primary health care through the health extension program / Zufan Abera Damtew, Meike Schleiff, Kebede Worku, Chala Tesfaye Chekagn, Seblewengel Lemma, Onaopemipo Abiodun, Mignote Solomon Haile, Dennis Carlson, Ahmed Moen, and Henry B. Perry -- Health improvement through primary health care approach : case of Nepal / Kedar Prasad Baral, Nadia Diamond-Smith, and Rita Thapa -- Four decades of community-based primary health care development in Ghana / James F. Phillips, Fred N. Binka, John Koku Awoonow-Williams, and Ayaga A. Bawah -- Sri Lanka's health improvements as an example of the implementation of the Alma-Ata declaration / Vinya Ariyarantne -- How Vietnam's Doi Moi reforms avhieved rapid gains in health with comprehensive primary health care / Nguyen Thanh Huong and Hoang Khanh Chi -- Cuba's progress on primary health care since the Alma-Ata conference / Sasmira Matta, David Bishai, and Pedro Más Bermejo -- Health for all in the twenty-first century : lessons for the next forty years of implementing primary health care / Meike Schleiff and David Bishai.