In this Forum article, we discuss issues emerging from utilizing two significant theoretical constructs, Funds of Knowledge and Cultural Capital, in the field of second/multilingual language studies. Some similar underlying characteristics yet opposite perspectives surrounding the concepts and theoretical applications have confused researchers and practitioners. Hence, we address three major issues related to social class-based knowledge distinction, little consideration of diversity and agency, and lack of empirical evidence on the convertibility and transferability of knowledges. Through the discussions, we pose important questions to seek diversity and equity of knowledges and urge applied linguists to raise their critical awareness of recognition and use/exchange value of second/multilingual learners' resources and knowledges.