To diversify the engineering workplace, we need to broaden participation in engineering. One way to broaden participation is through encouraging integration of engineering activities at home where parents, or more broadly caregivers, facilitate or support engineering activities for their children. This idea is reinforced by previous literature that identifies that (1) elementary-aged children can and should do engineering activities, (2) parents have a longstanding and significant impact on their children in many different ways, (3) parent-child relationships are unique and offer great potential for positive outcomes, and (4) parents can be effective in teaching engineering. While at-home engineering activities are already prevalent, the support resources attached to them are currently lacking for parents. This research is motivated by a desire to understand how parents think about and engage in engineering activities with their children to inform the most effective ways to support parents. This research is scoped to specifically look at the knowledge that 12 parents utilize in engineering activities and identify or perceive as being important in these activities. Given that there are many different types of engineering activities that exist, three different engineering activities that varied by level of structure were included in this study. The well-structured, semi-structured, and ill-structured activities all included a Marble Run toy and a storybook about Mars Rovers that was meant to support an authentic context for the activities. A multiple case study approach was used, where each case represented one of the activities with four parent participants in each case. Data collected for each parent participant included a pre-survey, observed activity engagement, reflection, and pre- and post-interviews. All of this data was coded with a priori codes from the Pedagogical Content Knowledge framework and emergent codes. The findings of this research highlight the role of the following on parent-child engagement in an engineering activity: the rhythm and routine of the parent-child dyad, external influences and independent individual experiences of the parent and the child, parents' ideas about engineering, and the structure of the activity. While the Pedagogical Content Knowledge framework was a useful tool for classification of knowledge, the research findings highlight the role of past experiences and external resources in shaping parents' views on the best way to support their children which is not well documented in this framework. These findings suggest that Frames of Practice may be a better theory to use in thinking about and studying parent-child engagement. Parents utilize existing frames of practice for engaging with their children to dictate the general teaching strategies to utilize. Within specific activities, they also refer to similar neighboring experiences and external resources to refine their frames of practice and modify their strategies used. While parents implement engineering knowledge and strategies, they do not recognize that what they are doing is engineering. There is also variation in the quantity and quality of strategies that are needed for engagement in the different activities, with less structure indicating more skills required of the facilitator and more positive outcomes for the child. For stakeholders invested in parent engagement, this research suggests that we need to (1) validate parents' existing and effective ideas about teaching and engineering by giving parents language that will help them refine their frames of practice through reflection, (2) encourage the use of more advanced pedagogical strategies or engineering strategies, (3) explicitly explain the value of them using the word engineering with their child and the value of continuing to use and talk about the engineering strategies they already implement (brainstorming, planning) with their child, and (4) ensure that parents see the potential engineering connections in the activity. / Doctor of Philosophy / Society needs more qualified engineers and one way to encourage a more diverse workforce is to support greater engagement in engineering at a young age in an effort to support interest development. One way to have more children engaging with engineering is to have parents, or more broadly caregivers, incorporate these activities at home with their children. Previous research has already shown that (1) elementary-aged children can and should do engineering activities, (2) parents have a longstanding and significant impact on their children in many different ways, (3) parent-child relationships are unique and offer great potential for positive outcomes, and (4) parents can be effective in teaching engineering. At-home learning is already prevalent and many engineering activities that parents can implement at home already exist, but the resources and information that come with these activities fall short of providing adequate support for parents. This research is motivated by a desire to understand how parents think about and engage in engineering activities with their children to inform the most effective ways to support parents. This research study describes how 12 parents think about and utilize information when engaging with their children in engineering activities. Many different types of engineering activities exist, and one of the ways in which they can be classified is by their level of structure. A well-structured, semi-structured, and ill-structured activity was included in this research where all activities included a Marble Run toy and a storybook about Mars Rovers that provided a realistic way to think about the activity in real-life terms. Each parent participant completed a pre-survey, observed activity engagement, reflection, and pre- and post-interviews as part of this research. To analyze this data, parent data was analyzed and contextualized prior to building cases formed around the different engineering activities. The findings of this research highlight the role of the following on parent-child engagement in an engineering activity: the rhythm and routine of the parent-child dyad, external influences and independent individual experiences of the parent and the child, parents' ideas about engineering, and the structure of the activity. Parents utilize existing ideas for engaging with their children to dictate the general teaching strategies they use, but they also refer to neighboring experiences and external resources to refine these ideas and modify their strategies used for the specific activity. While parents implement engineering knowledge and strategies, they do not recognize that what they are doing is engineering. There is also variation in the quantity and quality of strategies that are needed for engagement in the different activities, with less structure indicating more skills required of the facilitator and more positive outcomes for the child. For those invested in parent engagement, this research suggests that we need to (1) validate parents' existing and effective ideas about teaching and engineering by giving parents language that will help them refine their ideas about teaching engineering through reflection, (2) encourage the use of more advanced teaching strategies or engineering ideas, (3) explicitly explain the value of using the word engineering with their child and the value of continuing to use and talk about the engineering strategies they already implement (brainstorming, planning) with their child, and (4) ensure that parents see the potential for engineering connections in the activity.