  A consistent phenomenology of the interaction of particles of arbitrary spin
requires covariant spinors, field operators, propagators and model
interactions. Guided by an approach originally proposed by Weinberg, we
construct from group theoretical arguments the (j,0)+(0,j) covariant spinors
and the field operators for a massive particles. Specific examples are worked
out in the familiar language of the Bjorken and Drell text for the case of the
(1,0)+(0,1), (3/2,0)+(0,3/2) and (2,0)+(0,2) matter fields. The m\to 0 limit of
the covariant spinors is shown to have the expected structure. The algebra of
the \gamma^{\mu\nu} matrices associated with the (1,0)+(0,1) matter fields is
presented, and the conserved current derived. The procedure readily extends to
higher spins. The causality problem associated with the j\ge 1 wave equations
is discussed in detail and a systematic procedure to construct causal
propagators is provided. As an example a spin two wave equation satisfied by
the (2,0)+(0,2), covariant spinors is found to support not only ten correct and
causal solutions, but also thirty physically unacceptable acausal solutions.
However, we demonstrate how to construct the Feynman propagator for the higher
spin particles directly from the spinors and thus avoid the shortcomings of the
wave equation in building a phenomenology. The same exercise is repeated for
the (1,0)+(0,1) and (3/2,0)+(0,3/2) matter fields, and the same conclusions
obtained. Massless limit is discussed in detail. (Typos uncorrected, Part of
the work published and extended in several journal articles, for an important
correction see physics/9702005).
