His father was a captain in the Dutch army until his death at the siege of Ostend in early June 1602.
With his father usually not home (and eventually meeting his death) because of a military career, Van Rensselaer's mother sent him to apprentice with his uncle, Wolfert van Bijler, a jeweler and diamond merchant. At the time, the gem trade was a prosperous enterprise to join, being a well-developed craft. In those days, the diamond trade was nearly always combined with the trade in pearls, other articles of luxury, and rarities of every description. Dutch jewelers found a ready market for their valuable wares at the Dutch imperial court and the smaller German courts. This realm of work promoted Van Rensselaer to a life of economic success.
Much of Van Rensselaer's early life is unknown to today's historians, though in March 1608 it has been recorded that he was taking care of some business of Van Bijler in Prague. It seems Van Bijler gradually retired from his business, leaving it in the control of Van Rensselaer. During his tenure at the helm of his uncle's business, Van Rensselaer proposed a merger with the firm of Jan van Wely, and five Congressmen from New York between 1789 and 1842.
Van Rensselaer is also the source of the names of the town of Rensselaerville, city of Rensselaer, and county of Rensselaer in upstate New York. Additionally, Rensselaer Polytechnic Institute in Troy was founded in 1824 by Stephen Van Rensselaer III as the Rensselaer School. It is now a world-renowned technical and engineering school. Notably, at the time of his death, Stephen III was worth about $10 million (about $88 billion in 2007 dollars) and is noted as being the tenth-richest American in history.
Rensselaerswyck continued as a legal entity until the mid-1840s, having survived Dutch and British colonial times, even being given a special patent by Queen Anne to confirm the patroon's fiefdom upon British takeover of the area. The end of the manor came with the Anti-Rent War, when many tenants rose against the successors of Stephen Van Rensselaer III (who had died in 1839), having much influence on the Legislature elections of the time, and eventually intimidating the Van Rensselaer family enough to sell off most of its holdings.
The family records, many of which were translated and published in the Van Rensselaer Bowier Manuscripts, reveal the personality of the man who figures prominently in the history of colonization as the founder of the only successful patroonship that ever existed in New Netherland. But beyond the fact that he managed this patroonship and that he was a merchant and director of the West India Company, practically nothing was known until the organization and translation of the family records in the early 1900s (decade).