In a keynote talk given at the The 12th Workshop in Primary and Secondary Computing Education (WiPSCE) in Nijmegen (The Netherlands), I discussed how teachers from varied teaching background and computing experiences engage with online professional development materials. I used data from our online just-in-time professional development project (PD4CS), which is designed to support teachers’ traditional face-to-face PD experience. I presented how teachers with different teaching and computing backgrounds teaching computer science for the first time used PD4CS materials. Not surprisingly, we found that experienced CS teachers used online PD materials on a limited basis; however, novice-CS teachers used PD materials that focused on developing their pedagogical content knowledge and teachers with no CS background primarily used CS content knowledge PD materials. Here are the keynote slides.