Absolute oscillator strengths are calculated with intermediate coupling and configuration mixing in Si I. All possible transitions between the following configurations are considered: |$3s^23p^2,\enspace 3s^23pns,\enspace 3s^23pnf, \enspace 3s^23p3d+3s^23p4d+3s3p^3 $|, where n takes the values 4, 5, 6, 7. This involves some 2450 lines, many of which are of astrophysical importance. Radial wavefunctions are obtained from a semi-empirical method, basically a modification of the Scaled Thomas–Fermi approach used by Stewart & Rottenberg (8). The eigenvectors are from a least squares fit to the observed energy levels by Radziemski & Andrew (1). Where both the theoretical and experimental |$f$|-values are thought to be of high accuracy there is excellent agreement. An extensive comparison with solar line strengths is made in the following paper. This comparison allows a choice to be made between the various approaches to the calculation of |$f$|-values. It is found that the use of individual wavefunctions for each term within a configuration leads to better |$f$|-values than the adoption of one wave-function for an entire configuration. Attention is drawn to Section 10, which evaluates the reliability of |$f$|-values in different transition arrays. Magnetic dipole and electric quadrupole transitions within the |$3s^23p^2$| configuration are also tabulated.