  New mid-infrared period-luminosity (PL) relations are presented for \rrl{}
variables in the globular cluster M4 (NGC 6121). Accurate photometry was
obtained for 37 \rrl{} variables using observations from the Infrared Array
Camera onboard the Spitzer Space Telescope. The dispersion of M4's PL relations
is 0.056, and the uncertainty in the slope is 0.11 mag. Additionally,
weestablished calibrated PL relations at 3.6 and 4.5~\micron{} using published
Hubble Space Telescopegeometric parallaxes of five Galactic \rrl{} stars. The
resulting band-averaged distance modulus for M4 is $ \mu = 11.399 \pm 0.007
\textrm{(stat)} \pm 0.080 \textrm{(syst)} \pm 0.015 \textrm{(cal)} \pm 0.020
\textrm{(ext)}$. The systematic uncertainty will be greatly reduced when
parallaxes of more stars become available from the GAIA mission. Optical and
infrared period-color (PC) relations are also presented, and the lack of a MIR
PC relation suggests that \rrl{} stars are not affected by CO absorptionin the
4.5~\micron{} band.
