  We set constraints and future sensitivity projections on millicharged
particles (MCPs) based on electron scattering data in numerous neutrino
experiments, starting with MiniBooNE and the Liquid Scintillator Neutrino
Detector (LSND). Both experiments are found to provide new (and leading)
constraints in certain MCP mass windows: 5 - 35 MeV for LSND and 100 - 180 MeV
for MiniBooNE. Furthermore, we provide projections for the ongoing Fermilab SBN
program, the Deep Underground Neutrino Experiment (DUNE), and the proposed
Search for Hidden Particles (SHiP) experiment. In the SBN program, SBND and
MicroBooNE have the capacity to provide the leading bounds in the 100 - 300 MeV
mass regime. DUNE and SHiP are capable of probing parameter space for MCP
masses in the range of 5 MeV - 5 GeV that is significantly beyond the reach of
existing bounds, including those from collider searches and, in the case of
DUNE, the SLAC mQ experiment.
