What circumstances promoted and inhibited social reform in the early republic?

Well, social reform is a fairly broad topic, so let me address the ones I would think most pressing at the time.

In the case of both women and slaves, they both participated on different levels in the Revolutionary effort. Slaves often did so with the promise of freedom in exchange for military service.  Sometimes this was granted and sometimes not, but either way, the reform of individual and institutional slavery ran up against the racism of society (almost universally so) and the growth of slavery in the southern colonies.  That is, there was a chance once the Revolution was complete to reform the institution, but economic (the exanded reliance on southern slavery) and social factors (widespread racism and fear of a free black population) prevented this.

Right after the Revolution, women felt there was a chance to build a new society where women, if not equals, at least had rights and a place to start down that path.  Some women's schools were started in the 1780s, and Abigail Adams, wife of Constitutional Convention delegate John, famously urged him to "Remember the Ladies" while drafting the document.  The powerful social belief, however, that women belonged in the home (The Cult of Domesticity) raising children to be "virtuous members of the new Republic" (Republican Motherhood) meant that by early 1800, women were largely in no better a social position than they were before.