While research demonstrates the important role parents play in facilitating children's literacy development, little is known about the knowledge that underpins these exchanges. Here, we examined the association between parents' reading-related knowledge (phonological awareness, knowledge of syllable patterns, and identification of regular and irregular word spellings) and feedback across two contexts: responses to an unknown kindergartner's writing vignette (Task 1, N = 75) and mediation of a joint writing activity with the parents' own children (Task 2, n = 70). Parents' reading-related knowledge was positively associated with praise in both tasks. Parents' reading-related knowledge was also positively associated with modeling effective writing techniques in Task 1, but negatively associated with dictation (a lower form of scaffolding) in Task 2. Our findings demonstrate that parents generally display developmentally appropriate practices when helping children; parents with higher reading-related knowledge also appear to offer more supportive feedback when commenting on, or scaffolding, children's writing.