This study reviews 17 studies since the year of 2000 on the perceptions and practices of immigrant parents who reside in the United States or Canada with respect to their children's heritage language maintenance (HLM). The findings suggest that parental perceptions may change due to practical considerations and vary with different degrees of expectation, emphases, and reasons. To apply their attitudes into practice, the body of literature shows that parents take the responsibility to make efforts, through trying to make full use of the in-house and external resources such as creating language environment and attending heritage language school and church. However, some of them have little enthusiasm and some of them change their language practices. Also, there are discrepancies between what they think and what they practice. Several challenges are synthesized including children's changing language practices, their resistance to attending heritage language school, and parents' lack of time and energy. Further implications are discussed regarding children's bilingual/multilingual development, parental efforts, and external resources. It is concluded that joint efforts from parents, educational institutions, governments, and other organizations should be made to tackle the issues in HLM.