Population models predict that a large fraction of systems will undergo common
envelope (CE) evolution - a phase that dramatically impacts nebular outflows. I will
present a novel method to observationally determine the mapping between initial and
final conditions of CE evolution by characterizing a set of post-CE binaries in open
clusters. We recently completed a search in 299 clusters and identified 52 new systems (2
were previously known). Directly relating post-CE outcomes to their pre-CE parameters
provides benefits as simulations would have initial conditions and final outcomes that
their codes must reproduce, and population efforts could utilize observational mappings.