The purpose of this study is to explore Korean divorced mothers' experiences of noncustodial fathers' involvement in children's lives after divorce and co-parenting relationships. The data were collected from 17 mothers who were divorced between the years of 2004 and 2009, and were raising at least one minor child. Data were analyzed based on the inductive data analysis method. Divorced mothers' experiences of noncustodial fathers' involvement in children's lives after divorce were categorized in three ways: a satisfactory on-going relationship, a dissatisfactory on-going relationship, and a discontinued relationship. The results show that a few mothers were satisfied with the degree of the fathers' involvement in the children's lives 1) if the fathers were interested in their children and responsive to their children, and 2) if the fathers paid either child support or provided some financial supports for their children based on the fathers' financial abilities. However, the majority of the mothers were dissatisfied with the degree of the fathers' involvement in the children's lives. While some of the mothers maintained a relationship with the children's fathers despite their dissatisfaction, others discontinued the relationship. Regarding the co-parenting relationship after divorce, the relationships with the fathers were classified as either cooperative relationships or uncooperative relationships. The majority of the mothers experienced difficulties establishing cooperative co-parenting relationships with the fathers, but three mothers had cooperative relationships. The reasons for these uncooperative relationships were: uncooperative fathers, uncooperative mothers, or ambiguous communication regarding parenting after divorce. These findings suggest parenting education for divorced parents.