  In this work I review the observational constraints imposed on the energetics
and magnetisation of quasar jets, in the context of theoretical expectations.
The discussion is focused on issues regarding the jet production efficiency,
matter content, and particle acceleration. I show that if the ratio of
electron-positron-pairs to protons is of order $15$, as is required to achieve
agreement between jet powers computed using blazar spectral fits and those
computed using radio-lobe calorimetry, the magnetization of blazar jets in
flat-spectrum-radio-quasars (FSRQ) must be significant. This result favors the
reconnection mechanism for particle acceleration and explains the large
Compton-dominance of blazar spectra that is often observed, without the need to
postulate very low jet magnetization.
