Only a few molecules have Zeeman splitting factors large enough to be successfully used to measure magnetic fields. Of these few, OH traces lower density molecular species, while CN is believed to trace higher density regions. Using the Green Bank Telescope (GBT) we mapped the magnetic fields of cores and envelopes of dark cloud cores using OH as a tracer molecule. From this, the ratio of M/phi between the cores and envelopes were computed, and were consistently determined to be 1. This is inconsistent with published ambipolar diffusion theory which expects this ratio to be 1. This study can be extended to other types of objects by using different tracer molecules. CN can be used to probe hot dense regions; however, it requires high resolution mapping currently only obtainable with an interferometer. Using CARMA, we obtained maps of 6 high mass star formation regions with a spatial resolution of approximately 2" by combining data from the C, D, and E arrays.^