Ordered that the order is affirmed insofar as appealed from, without costs or disbursements.
Custody determinations are ordinarily a matter of discretion for the trial court, and its determination, based upon a firsthand assessment of the parties, their credibility, character, and temperament, should be accorded great deference on appeal (see Matter of Krebsbach v Gallagher, 181 AD2d 363 [1992]). The trial court’s determination that it is in the child’s best interest to transfer his custody from the mother to the father has a sound and substantial basis in the record.
We recognize that “[p]riority, not as an absolute but as a weighty factor, should, in the absence of extraordinary circumstances, be accorded to the first custody awarded in litigation or by voluntary agreement” (Matter of Nehra v Uhlar, 43 NY2d 242, 251 [1977]), based upon the belief that the stability this policy will assure in the child’s life is in the child’s best interest (see Eschbach v Eschbach, 56 NY2d 167, 171 [1982]). Nevertheless, under the circumstances of this case, the mother and the Law Guardian overstate the likelihood of disruption in the child’s life resulting from the transfer of custody from the mother, with whom, by virtue of the parties’ agreement, the child has resided since the parents separated.
The child spent the first five years of his life in the home where the father resides, and has regularly visited with the father there since the parents separated. He attended parochial school near there, and recently attended religious instruction and received his first communion at the church affiliated with that same school. There was evidence that the child had friends and relatives in the father’s neighborhood. Moreover, we find no basis to disturb the trial court’s findings that the father has demonstrated more stability than the mother, and that the mother tended to make unilateral decisions concerning the child.