The district court denied appellant’s petition for modification of a custody decree regarding primary custody of two of the parties’ minor children. Appellant appeals and states the issue to be:
Did the trial court abuse its discretion and thus err as a matter of law by failing to consider the best interests of the children and by considering instead only the circumstances of the mother in a child custody modification proceeding?
We affirm.
On March 2, 1979, the parties were divorced and appellant (mother) was awarded the primary care, custody and control of the parties’ children, with appellee (father) being awarded rights of visitation.1 At the request of appellant in June 1985, the children went to reside with appellee. On April 24, 1986, appellee filed a Petition for Modification of Divorce Decree seeking primary custody of the parties’ children. After a hearing the court found a substantial change in the circumstances and modified the divorce decree to give appellee primary custody of the two youngest children, FV and BV. The order was dated March 4, 1987.
At the beginning of the summer of 1987, FV and BV went to Washington to visit appellant. At the end of the summer, appellant refused to return the children to appellee in Wyoming. Appellee and appellant both agreed to enroll the children in school in Washington. In January 1988, appellee informed appellant that he was coming to Washington to get the children at the end of the school semester. Before appellee left for Washington, he was served with a temporary restraining order from a Washington court preventing him from going to Washington to take the children. Appellee contested the Washington *217court action. The trial court in Wyoming and the Washington court agreed that neither state would make any determinations in this case during the school year. In August of 1988, the children were returned to appellee’s custody in Wyoming.
Appellee resides in Worland, Wyoming with his father and the two children. Other relatives of appellee in the Worland area include a brother and his family and a sister and her family. Appellee’s sister, an older woman, has taken a special interest in FV and is someone with whom the child feels she can talk. Appellee has been employed for five years at Imperial Holly Sugar Corporation in Worland with the possibility of advancement. The children attend school in Worland, are involved in sports and have friends who are involved in many activities with them. The guardian ad litem stated that the children could survive very well with either parent. Appellant does not contend that appellee provides a bad home for the children.
Certain basic rules of appellate review are applicable here. The reviewing court examines the evidence in the light most favorable to the prevailing party, presumes it is true, and leaves out of consideration entirely the evidence presented by the unsuccessful party that conflicts with the successful party’s evidence. Furthermore, the reviewing court may make every favorable inference that may reasonably and fairly be drawn from the evidence produced by the successful party. We will not interfere with the decision of the district court and accord its factual determinations great deference unless there is a procedural error or a clear abuse of discretion. An abuse of discretion has been said to mean an error of law committed by the court under the circumstances. In determining whether there has been an abuse of discretion, the' ultimate issue is whether or not the court could reasonably conclude as it did. A reviewing court cannot substitute its judgment for that of the trial court, whose judgment must be sustained unless clearly erroneous, manifestly wrong, or totally against the evidence. The appellate court will not set aside the trial court’s findings merely because it might have reached a different result. See Pancratz Company, Inc. v. Kloefkorn-Ballard Construction/Development, 720 P.2d 906 (Wyo.1986); Wangler v. Federer, 714 P.2d 1209 (Wyo.1986); Yates v. Yates, 702 P.2d 1252 (Wyo.1985); Lebsack v. Town of Torrington, 698 P.2d 1141 (Wyo.1985); Scott v. Fagan, 684 P.2d 805 (Wyo.1984); State ex rel. Wyoming Worker’s Compensation Division v. Colvin, 681 P.2d 269 (Wyo.1984); Consolidated Freightways v. Drake, 678 P.2d 874 (Wyo.1984); Doenz v. Garber, 665 P.2d 932 (Wyo.1983); Ayling v. Ayling, 661 P.2d 1054 (Wyo.1983); City of Rock Springs v. Police Protection Association, 610 P.2d 975 (Wyo.1980); Arch Sellery, Inc. v. Simpson, 360 P.2d 911 (Wyo.1961).
In Kreuter v. Kreuter, 728 P.2d 1129, 1130 (Wyo.1986) (footnote omitted), we said:
Section 20-2-113(a), W.S.1977, Cum.Supp.1986, provides for modification of provisions for custody and support in divorce decrees but the “circumstances" there referred to must be a substantial or material change of circumstances which outweigh society’s interest in applying the doctrine of res judicata to a final decree of divorce. There must be an end to litigation at some point, or the legal system would become bogged down so that nothing would ever remain decided. Mentock v. Mentock, Wyo., 638 P.2d 156 (1981). The burden of proof lies with the party seeking the modification that a substantial or material change has occurred subsequent to the decree. Nuspl v. Nuspl, Wyo., 717 P.2d 341 (1986); Cubin v. Cubin, Wyo., 685 P.2d 680, 684 (1984).
Decisions regarding child support and custody rest largely with the district court which we will not disturb in the absence of a grave abuse of discretion or violation of some legal principle. Nuspl v. Nuspl, supra; Harrington v. Harrington, Wyo., 660 P.2d 356, 360 (1983).
The only changes that occurred between the court’s March 1987 order and the October 3, 1988, hearing, other than the fact that the children are older, are that appellant has remarried, her income has in*218creased, and she can obtain and has obtained insurance for the children. The trial court did not abuse its discretion in finding that appellant failed to show a substantial change in circumstances.
The main thrust of appellant’s appeal is that the court did not consider the best interests of the children and did not honor the children’s preference regarding custody. The trial court's decision letter dated October 7, 1988, which is incorporated into its order of October 18, 1988, sets out W.S. 20-2-113(a) which provides in pertinent part:
[T]he court may make such disposition of the children as appears most expedient and beneficial for the well-being of the children. * * * On the petition of either of the parents, the court may revise the decree concerning the care, custody, visitation and maintenance of the children as the circumstances of the parents and the benefit of the children requires.
It is undisputed that the trial court must always consider the best interests of the children in custody matters. Fanning v. Fanning, 717 P.2d 346 (Wyo.1986); Mentock v. Mentock, 638 P.2d 156 (Wyo.1981); Wilson v. Wilson, 473 P.2d 595 (Wyo.1970); Taylor v. Taylor, 388 P.2d 192 (Wyo.1964); Henson v. Henson, 384 P.2d 721 (Wyo.1963). It is obvious here that the trial court was aware of, and did consider, the best interests of the children. This is demonstrated by the court’s recital of the controlling statute in his decision letter.
The trial court applied the correct law; there was no procedural error nor any clear abuse of discretion. Basing its decision on the evidence before it, the court did not act in a manner which exceeded the bounds of reason under the circumstances, and the conclusion it reached was arrived at reasonably. Therefore, the trial court did not err in denying appellant’s petition.
Appellant contends that the custody award was made contrary to the preference of the children. In Yates, 702 P.2d at 1256 (citation omitted), this court said:
The preference of a child of sufficient age and maturity is a factor to be considered by a court in ascertaining what is in the child’s best interests. In Tytler v. Tytler, 15 Wyo. 319, 338, 89 P. 1, 6 (1907), the court stated:
“ * * * Such we think is the general rule; for, if the happiness and welfare of the infant is to be consulted, nothing could be more potent upon that question than the expression of its preference based upon kindness or unkindness, care or want of care, love and affection or want thereof, and, as to the surrounding conditions, either with one or the other.”
“It appears to be the almost universal rule that at least when a child is of sufficient age, intelligence, and discretion to exercise an enlightened judgment as to its future welfare, based upon facts and not mere whims, its wishes are one factor which may be considered by the court in determining custody, in doubtful cases in any event, usually not because of any legal right in the child to have its wishes granted, but because the consideration of such wishes will aid the court in making a custodial decree which is for the best interests and welfare of the child. * * * ” 4 A.L.R.3d 1396, 1402 Custody-Child’s Wishes (1965).
Courts in other jurisdictions have taken into consideration the wishes of children when determining custody, duPont v. duPont, 59 Del. 206, 216 A.2d 674 (1966); State ex rel. Waslie v. Waslie, 274 Minn. 564, 143 N.W.2d 634 (1966); In re Marriage of Kramer, 177 Mont. 61, 580 P.2d 439 (1978). In Kramer the court held:
“We are committed to the view that the welfare of the children is the paramount consideration in awarding custody. [Citations.] We believe the welfare of the children, particularly children of the ages involved here [the ages of the children involved were 11, 13, and 15] is not being served if their wishes are not considered by the trial court.” Id., at 444.
* * * In addition, the preference which has a stated basis and is expressed in a plain manner should be accorded greater *219weight than one whose basis cannot be described. This is not to say that the preference of a minor child is controlling upon the court.
In determining the weight to be given a child’s preference several factors should be considered: the age of the child; the reason for the preference; the relative fitness of the preferred and non-preferred parent; the hostility, if any, of the child to the non-preferred parent; the preference of other siblings; and whether the child’s preference has been tainted or influenced by one parent against the other.
Although custodial preference is not conclusive, the court here was entitled to give more consideration to a fifteen-year old girl’s preference than say, the preference of a six-year old child. * * *
* * * We accord great deference to a trial judge’s factual determination. The judge hearing a modification petition is in a better position to determine the credibility of a witness and the value of the testimony. Stirrett v. Stirrett, 35 Wyo. 206, 248 P. 1 (1926).
Bill Shelledy, guardian ad litem, reported to the court in chambers regarding the children’s preferences with respect to custody. Mr. Shelledy interviewed the children on or about September 14, 1988, less than a month after they returned from Washington. Mr, Shelledy stated to the court:
I asked, at first I just asked [the children], who would you prefer to live with. Neither one of the children wanted to state, you know, there wasn’t anything immediately jumping out, I want to be here, I want to be there. So, I asked them, ok[ay], where would you want to live. They all said Washington. Both of them said Washington. The reasons for Washington, [FV] was the mall and [BV] was his paper route and friends.
* * * * * *
I tried to get around to — they said that they wanted to live in Washington. The next question I asked, well, I said, if your dad lived in Washington and your mom lived in Worland, where would you want to live? And then they changed it around. They wanted to live in Worland. Basically, when it got around to — the way they answered the questions, though, they would not come out and say specifically, I want to live with my mother rather than my father. There were— the answers to the questions turn to the fact that I had the feeling that they wanted to live with their mother.
I asked questions about what they like, what they dislike of each. After being sitting here in Court, I find it very interesting because there was more conversation about their mother, likes and dislikes, just as she was in court more talkative than Frank. They couldn’t think of any dislikes or likes immediately about Frank, in fact had very little discussion about Frank. They were more discussing their mother and a different relationship. But it appears to me that it’s the same type of thing that it appeared to me, that Frank is very inward and quiet and Ermina is more of an outgoing person, and that’s the way the kids discussed it.
My end feeling was that the children could survive and survive very well from dealing with them in either place. The kids to me seem extremely well adjusted, and, of course, they had been through this procedure before. But they haven’t been disrupted by moving back and forth, and they said, you know, I’ve got friends in Washington, I’ve got friends in Worland, I can, you know, in fact can and do move back quite a bit and did not seem to be upset about moving back and forth.
I guess the bottom line is if the Court would ask, or the kids would ask I think if I could get them to come out and specifically say, they would prefer to live with their mother.
If the children had actually been in court, the court would have been able to witness their demeanor and ask more searching or specific questions. With the benefit of seeing and hearing the children, the court might have been able to give their testimony greater weight and better evaluate such *220testimony. The children’s stated custodial preference is rather tenuous and equivocal.2 This is understandable because likely the children did not want to offend either parent. Also, some of their reasons for favoring their mother’s custody were insubstantial. We cannot say that the court abused its discretion in declining to change custody.
Were we to reverse the trial court, we would necessarily have to weigh and evaluate the evidence differently than did that court. We also would be substituting our judgment for that of the trial court. This is contrary to our appellate rules.
Affirmed.
URBIGKIT, J., filed a dissenting opinion.
. There were four children bom of the parties' marriage. Only the two youngest children are involved here. The eldest is emancipated. The next eldest resides with her mother.
. W.S. 3-2-107 pertains to preference for appointment of guardian of a minor. Understandably, this statute was not urged by appellant at trial nor on appeal.