In this presentation three recent contributions to the theory of continuum (or “Fro¨hlich”‐) polarons are discussed. (i) Using a generalization of the Jensen‐Feynman variational principle within the path‐integral formalism for identical particles, the ground‐state energy of a confinedN‐polaron system is studied as a function ofNand of the electron‐phonon coupling strength. (ii) Cyclotron‐resonance (CR) spectra of a gas of interacting polarons in a GaAs/AlAs quantum well are theoretically investigated taking into account the magnetoplasmon‐phonon mixing and the band non‐parabolicity. The calculated CR spectra are in a good agreement with experimental data. The theory explains that, for a high‐density polaron gas, anticrossing of the CR spectra occurs near the GaAs TO‐phonon frequency rather than near the GaAs LO‐frequency. (iii) A theoretical investigation of the optical properties of stacked quantum dots is presented, which is based on the non‐adiabatic approach. © 2003 American Institute of Physics