A cikin ƙarni na 16, ƙungiyoyin gyare-gyare na Furotesta sun yi zurfafa shiga cikin Kiristanci na Poland da kuma sakamakon sake fasalin Poland ya ƙunshi ɗarikoki daban-daban.Manufofin haɗin kai na addini da aka bunƙasa a Poland kusan babu kamarsu a Turai a lokacin kuma da yawa waɗanda suka tsere daga yankunan da rikicin addini ya daidaita sun sami mafaka a Poland.Sarautar Sarki Sigismund na Tsohon (1506 – 1548) da Sarki Sigismund II Augustus (1548 – 1572) sun shaida tsananin noman al’adu da kimiyya ( Zamanin Zinare na Renaissance a Poland), wanda masanin astronomer Nicolaus Copernicus (1473) -1543) shine mafi kyawun wakilci.Jan Kochanowski (1530-1584) mawaƙi ne kuma firaministan fasaha na lokacin.A cikin 1525, a lokacin mulkin Sigismund I, an ba da umarnin Teutonic kuma Duke Albert ya yi wani abin girmamawa a gaban Sarkin Poland (Prussian Homage) don fief, Duchy na Prussia.Mazovia a ƙarshe an haɗa shi da cikakken shiga cikin Crown Yaren mutanen Poland a cikin 1529.Mulkin Sigismund II ya ƙare lokacin Jagiellonian, amma ya haifar da Union of Lublin (1569), cikakkiyar cikar haɗin gwiwa tare da Lithuania.Wannan yarjejeniya ta canja Ukraine daga Grand Duchy na Lithuania zuwa Poland kuma ta canza tsarin mulkin Poland-Lithuania zuwa wata ƙungiya ta gaske, ta kiyaye shi fiye da mutuwar Sigismund II mara haihuwa, wanda aikin sa ya sa kammala wannan tsari ya yiwu.Kasar Poland ta hada Livonia a arewa maso gabas a shekara ta 1561 kuma Poland ta shiga yakin Livonia da Tsardom na Rasha .Ƙungiyar kashe-kashen, wadda ta yi ƙoƙarin duba ci gaba da mulkin jihar da manyan iyalai na Poland da Lithuania, suka yi a Sejm a Piotrków a 1562-63.A fagen addini, ’yan’uwa na Poland sun rabu da ’yan Calvin, kuma an buga Littafi Mai Tsarki na Protestant Brest a shekara ta 1563. ’Yan Jesuit, da suka zo a 1564, an ƙaddara su yi tasiri sosai a tarihin Poland.