Although captive-taking by the Ukrainian and Don Cossacks in the Crimean Khanate and Ottoman Empire has long been evident in well-known sources stemming from Poland – Lithuania and Muscovy, for the most part this activity has been ignored or considered negligible by many historians, especially when compared with the Tatar – Ottoman slaving enterprise. Ottoman sources along with records from the above-mentioned states leave no doubt that Muslim and non-Muslim captives were a significant component of the hauls of cossack raids. Gain from ransom, both at or near the site of raids and in cossack home territories, was a clear motivating factor. The fate of captives who did not return to their native lands varied; it included concubinage/marriage, slave labour, and assimilation as free persons. In the early modern period a variety of forms of unfreedom were attested in Muscovy, the Kingdom of Poland, and the Grand Duchy of Lithuania. Muslim Tatars, Nogays, and Turks from the southern frontier, the unfree demographic of main interest here, were found in all three lands as de jure slaves, imprisoned de facto slaves, nearly free settlers, and persons whose degree of unfreedom was somewhere between these states. While the Don Cossacks were known to sell captives into slavery in Muscovy, less is known about the Ukrainian Cossacks, though they had a practice of donating captives to personages of high standing in Poland – Lithuania as “knightly gifts”. At present there is not enough information to make any firm conclusions as to the number of captives taken, other than that it was not insignificant but on a much smaller scale than those captured in the Tatar and Nogay slaving raids. The chapter discusses issues of categorization (ethnic, religious, geographic, occupational) and broader nomenclature (slavery versus captivity; spectra versus continua of unfreedom). The argument put forward is that, aside from Muscovy, unfreedom is a more meaningful concept than slavery in the region discussed in this study.